# 6.18: Prices Involving Sales Tax

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

**Practice**Prices Involving Sales Tax

Have you ever had to calculate a tip in a restaurant?

Sasha and Keith went out for lunch. Their total bill was $16.60. Both Sasha and Keith were puzzled when it came to calculating the tip. They decided to give the waiter a 15% tip.

Do you know how to calculate this?

What range would be an acceptable tip?

**This Concept is about estimate appropriate tips. You will learn how to tackle this problem.**

### Guidance

When you go to a restaurant, it is customary to tip the server. If you have help at the airport, it is customary to tip the server. If you have someone carry your bags at a hotel, it is customary to tip the bellhop.

**What is a tip?**

A *tip* is an amount of money that is given to a worker such as a waiter or waitress who performs a service for you. A common tip amount is 15% of the cost of the meal or other service. Since you don’t usually calculate a tip exactly, we can ** estimate** the amount of a tip.

**Follow these steps to estimate a 15% tip**

**Step 1: Round the total bill to the nearest whole dollar amount.**

**Step 2: Find 10% of this amount by moving the decimal point one place to the left.**

**Step 3: Find half of the amount you found in Step 2. This will give you 5% of the total cost.**

**Step 4: Add the 10% amount and the 5% amount together.**

*Take a few minutes to write these steps in your notebook.*

Now let’s apply these steps to a few situations.

Estimate a 15% tip on a meal whose cost is $29.75.

**Step 1: Round $29.75 to $30.**

**Step 2: 10% of \begin{align*}\$ 30 = \$ 3\end{align*}**

**Step 3: Half of** \begin{align*}\$ 3 = \$ 1.50\end{align*}

**Step 4:** \begin{align*}\$ 3 + \$ 1.50 = \$ 4.50\end{align*}

**A 15% tip on a meal whose cost is $29.75 is about $4.50.**

Estimate a 20% tip on a meal whose cost is $54.15.

**Since the tip is about 20%, you can find 10% and then double it.**

**Step 1: Round $54.15 to $54.**

**Step 2: 10% of** \begin{align*}\$ 54 = \$ 5.40\end{align*}

**Step 3: 20% of** \begin{align*}\$ 5.40 = 2 \times \$ 5.40 = \$ 10.80\end{align*}

**A 20% tip on a meal whose cost is $54.15 is about $10.80.**

Estimate a 15% tip for each bill. Provide a range in your answer.

#### Example A

$29.00

**Solution: \begin{align*}$3.00 - $3.50\end{align*}**

#### Example B

$16.00

**Solution:\begin{align*}$2.00 -$2.50\end{align*}**

#### Example C

$55.00

**Solution:\begin{align*}$8.00 - $8.50\end{align*}**

Here is the original problem once again.

Sasha and Keith went out for lunch. Their total bill was $16.60. Both Sasha and Keith were puzzled when it came to calculating the tip. They decided to give the waiter a 15% tip.

Do you know how to calculate this?

What range would be an acceptable tip?

To figure this out, first let's round up.

\begin{align*}16.60\end{align*} becomes \begin{align*}17.00\end{align*}

Now take 10% of that figure.

\begin{align*}1.70\end{align*}

Half of that is \begin{align*}.85\end{align*}.

If we add the two together, we get an estimate of </math>2.55</math>.

**A reasonable tip would be between \begin{align*}$2.50 - $3.00\end{align*}.**

### Vocabulary

Here are the vocabulary words in this Concept.

- Tip
- a percent that is added to a price or given for a service.

- Estimate
- an approximate calculation. It is not exact.

### Guided Practice

Here is one for you to try on your own.

Estimate a 20% tip on a restaurant bill of $38.95.

**Answer**

You can start by thinking about 10% of this bill. Since that involves simply moving the decimal point, we can say that the estimate of 10% is \begin{align*}$3.85\end{align*}.

Now 20% is double that.

We can say that an estimate of a 20% tip is in a range from \begin{align*}$7.50 - $8.00\end{align*}.

**This is our answer.**

### Video Review

Here is a video for review.

- This is a James Sousa video on calculating a tip.

### Practice

Directions:Estimate a tip of 20% for each amount.

1. A tip on $15.00

2. A tip on $28.00

3. A tip on $25.00

4. A tip on $35.00

5. A tip on $45.00

6. A tip on $50.00

7. A tip on $90.00

8. A tip on $120.00

9. A tip on $125.00

10. A tip on $110.50

11. A tip on $130.75

12. A tip on $135.50

13. A tip on $98.78

14. A tip on $89.67

15. A tip on $100.20

Discount

When a product is discounted, the price is reduced. The discount is the difference between the original and reduced prices.Percent

Percent means out of 100. It is a quantity written with a % sign.Proportion

A proportion is an equation that shows two equivalent ratios.Sales Tax

Sales tax is a small percentage of the sales price of a purchase, collected to support government services.### Image Attributions

Here you'll learn to estimate appropriate tips.

## Concept Nodes:

Discount

When a product is discounted, the price is reduced. The discount is the difference between the original and reduced prices.Percent

Percent means out of 100. It is a quantity written with a % sign.Proportion

A proportion is an equation that shows two equivalent ratios.Sales Tax

Sales tax is a small percentage of the sales price of a purchase, collected to support government services.