# 5.7: Better Buy 3

**At Grade**Created by: CK-12

Look at the signs below for the price of yo-yos at two different stores. Which store has the better buy for one yo-yo? In this concept, we will practice finding the unit price of items in order to determine which store has the better buy.

### Guidance

In order to figure out which item is the better buy, like in the question above, we can use the problem solving steps to help.

- Start by
**describing**what you see the pictures. - Next, figure out what
**your job**is in this problem. In all of these problems your job will be to figure out which item is the better buy. - Then, make a
**plan**for how you will solve. In these problems, you will want to figure out the unit price of the item at each store. Then, figure out which unit price is less. - Next,
**solve**the problem. - Finally,
**check**to make sure that the unit price at the store you chose is lower.

#### Example A

Which store has the better buy for one paddle and ball? How much is the paddle and ball at that store?

**Solution:**

We can use problem solving steps to help.

\begin{align*}& \mathbf{Describe} && \text{I see signs for paddles and balls at two stores.}\\ &&& \text{Jim's Sports} : \ 4 \ \text{paddles and balls for} \ \$20\\ &&& \text{A-One Athlete} : \ 3 \ \text{paddles and balls for} \ \$18\\ & \mathbf{My \ Job} && \text{Decide which store has the better buy for one paddle and ball set.}\\ &&& \text{Better buy means it costs less.}\\ & \mathbf{Plan} && \text{I'll figure out the price for one paddle and ball set at each store.} \\ &&& \text{Then I will compare the prices.}\\ & \mathbf{Solve} && \text{Jim's Sports}: \ \$20 \div 4 = \$5 \ \text{for one paddle and ball set}\\ &&& \text{A-One Athlete}: \ \$18 \div 3 = \$6 \ \text{for one paddle and ball set}\\ &&& \text{Jim's Sports has the better buy}\\ & \mathbf{Check} && \$5 < \$6 \ \text{so one paddle and ball set costs less at Jim's Sports.}\end{align*}

#### Example B

Which store has the better buy for one Frisbee? How much is one Frisbee at that store?

**Solution:**

We can use problem solving steps to help.

\begin{align*}& \mathbf{Describe} && \text{I see signs for frisbees at two stores.}\\ &&& \text{Jim's Sports} : \ 2 \ \text{frisbees for} \ \$6\\ &&& \text{A-One Athlete} : \ 5 \ \text{frisbees for} \ \$10\\ & \mathbf{My \ Job} && \text{Decide which store has the better buy for one frisbee.}\\ &&& \text{Better buy means it costs less.}\\ & \mathbf{Plan} && \text{I'll figure out the price for one frisbee at each store.} \\ &&& \text{Then I will compare the prices.}\\ & \mathbf{Solve} && \text{Jim's Sports}: \ \$6 \div 2 = \$3 \ \text{for one frisbee}\\ &&& \text{A-One Athlete}: \ \$10 \div 5 = \$2 \ \text{for one frisbee}\\ &&& \text{A-One Athlete has the better buy}\\ & \mathbf{Check} && \$2 < \$3 \ \text{so one frisbee costs less at A-One Athlete.}\end{align*}

#### Example C

Which store has the better buy? How much less are 2 boxes of cereal at that store?

**Solution:**

We can use problem solving steps to help.

\begin{align*}& \mathbf{Describe} && \text{I see signs for boxes of cereal at two stores.}\\ &&& \text{Borson's Foods} : \ 4 \ \text{boxes for} \ \$12\\ &&& \text{Saferoad Market} : \ 5 \ \text{boxes for} \ \$20\\ & \mathbf{My \ Job} && \text{Figure out which store has the better price for two boxes of cereal.}\\ &&& \text{Then compare prices to find out how much less.}\\ & \mathbf{Plan} && \text{I'll figure out the price of one box at each store. Then I can find the price for two}\\ &&&\text{boxes and compare the total prices.} \\ & \mathbf{Solve} && \text{Borson's Foods} : \ 4 \ \text{boxes for} \ \$12 \ \text{is} \ 12 \div 4, \ \text{or} \ \$3 \ \text{for one box and} \ \$6 \ \text{for} \ 2 \ \text{boxes.}\\ &&& \text{Saferoad Market} : \ 5 \ \text{boxes for} \ \$20 \ \text{is} \ 20 \div 5, \ \text{or} \ \$4 \ \text{for one box and} \ \$8 \ \text{for} \ 2 \ \text{boxes.}\\ &&& \$8 - \$6 = \$2. \ \text{I will save} \ \$2 \ \text{by buying cereal at Borson's Foods.}\\ & \mathbf{Check} && \text{Borson's Foods} : \ \$12 \div 4 = \$3 \ \text{and} \ 2 \times \$3 = \$6\\ &&& \text{Saferoad Market} : \ \$20 \div 5 = \$4 \ \text{and} \ 2 \times \$4 = \$8\\ &&& \$8 - \$6 = \$2\end{align*}

#### Concept Problem Revisited

We can use problem solving steps to help.

\begin{align*}& \mathbf{Describe} && \text{I see signs for yo-yos at two stores.}\\ &&& \text{Terry's Toys} : \ 3 \ \text{yo-yos for} \ \$12\\ &&& \text{Geena's Gifts} : \ 5 \ \text{yo-yos for} \ \$15\\ & \mathbf{My \ Job} && \text{Decide which store has the better buy for one yo-yo.}\\ &&& \text{Better buy means it costs less.}\\ & \mathbf{Plan} && \text{I'll figure out the price for one yo-yo at each store.} \\ &&& \text{Then I will compare the prices.}\\ & \mathbf{Solve} && \text{Terry's Toys}: \ \$12 \div 3 = \$4 \ \text{for one yo-yo}\\ &&& \text{Geena's Gifts}: \ \$15 \div 5 = \$3 \ \text{for one yo-yo}\\ &&& \text{Geena's Gifts has the better buy}\\ & \mathbf{Check} && \$3 < \$4 \ \text{so one yo-yo costs less at Geena's.}\end{align*}

### Vocabulary

A ** unit price** is the cost of one item. In this concept, we are given the overall price for multiple items and need to find the

**in order to figure out which store has the better buy.**

*unit price*### Guided Practice

1. Which store has the better buy for one racquet? How much is one racquet at that store?

2. Which store has the better buy for one golf ball? How much is one golf ball at the store?

3. Which store has the better buy? How much less are 2 gallons of milk at that store?

4. Which store has the better buy? How much less are 3 bottles of orange juice at that store?

**Answers:**

1. Jim’s Sports; \begin{align*}\$36 \div 6\end{align*}, or $6 for one badminton racquet (\begin{align*}\$28 \div 4\end{align*}, or $7 at A-One Athlete).

2. A-One Athlete; \begin{align*}\$30 \div 10\end{align*}, or $3 for one golf ball (\begin{align*}\$24 \div 6\end{align*}, or $4 at Jim’s Sports).

3. 2 bottles of milk cost $2 less at Morsel’s Market. $6 for 2 gallons of milk at Morsel’s Market (Unit price is $3/gallon). $8 for 2 gallons of milk at Flynn’s Foods (Unit price is $4/gallon).

4. 3 bottles of orange juice cost $3 less at Flynn’s Foods. $15 for 3 bottles of orange juice at Flynn’s Foods (Unit price is $5/bottle). $18 for 3 bottles of orange juice at Morsel’s Market (Unit price is $6/bottle).

### Practice

1. Which store has the better buy for one mug? How much less are 2 mugs at that store?

2. Which store has the better buy for one soup bowl? How much less are 3 soup bowls at that store?

3. Which store has the better buy for one water bottle? How much less are 5 water bottles?

4. Which store has the better buy for one birdie? How much is one birdie at the store?

5. Which store has the better buy for one can of tennis balls? How much is one can at that store?

6. Which store has the better buy for one box of pencils? How did you decide?

7. Which store has the better buy for one notebook? How did you figure it out?

8. Which store has the better buy for one box of paperclips? How did you figure it out?

9. Which store has the better buy for one box of nails? How did you figure it out?

10. Which store has the better buy for one stool? How did you figure it out?

11. Which store has the better buy for one hose? How did you figure it out?

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### Image Attributions

In this concept, students determine the unit price of an item at two different stores in order to figure out which store has the better buy. They also describe how much less expensive it is to buy items at one store vs. the other. Students use problem solving steps to help them to solve the problems.