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8.3: Circle Sums 6

Difficulty Level: At Grade Created by: CK-12

Look at the picture below. The arrows point to the sum of each row or column. Can you figure out the value of each of the four letters? In this concept, we will practice solving for unknowns in circles and arrows diagrams.

Guidance

In order to solve the problem above, use the problem solving steps.

• Start by describing what you see in the diagram.
• Next, figure out what your job is in this problem. In all of these problems your job will be to figure out the value of the four letters in the diagram.
• Then, make a plan for how you will solve. There is usually more than one way to solve the problem. In some of these problems you might need to find the sum of three letters first in order to find the value of one letter.
• Next, solve the problem.
• Finally, check to make sure that the values you found work for all seven of the arrows.

Example A

The arrows point to the sum of each row or column. Figure out the value of each letter.

Solution:

We can use problem solving steps to help.

Example B

The arrows point to the sum of each row or column. Figure out the value of each letter.

Solution:

We can use problem solving steps to help.

Example C

The arrows point to the sum of each row or column. Figure out the value of each letter.

Solution:

We can use problem solving steps to help.

Concept Problem Revisited

We can use problem solving steps to help.

Vocabulary

In math, an unknown is a letter that stands for a number that we do not yet know the value of. In this concept, when you figured out the value of the letters in the circles and arrows diagrams you were solving for unknowns.

Guided Practice

1. The arrows point to the sum of each row or column. Figure out the value of each letter.

2. The arrows point to the sum of each row or column. Figure out the value of each letter.

3. The arrows point to the sum of each row or column. Figure out the value of each letter.

1. \begin{align*}A = 5, \ B = 9, \ C = 7, \ D = 8\end{align*}

2. \begin{align*}A = 9, \ B = 6, \ C = 7, \ D = 3\end{align*}

3. \begin{align*}A = 8, \ B = 7, \ C = 5, \ D = 9\end{align*}

Explore More

For each problem, the arrows point to the sum of each row or column. Figure out the value of each letter.

Date Created:

Jan 18, 2013

Dec 29, 2014
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