Angles that form a linear pair combine to form a straight angle. (A straight angle measures 180 degrees.) The following practice questions ask you to solve problems based on linear pairs.

## Practice questions

In the following figure,

at E. In the following questions, fill in the blank to make the statement true.

If you know that

are represented by 2

*a*, 2*a*+*b*, and 3*a*– 20, respectively then*b*= ———?If you know that

## Answers and explanations

20

Start with the given information:

form a linear pair, which means their sum is 180 degrees. Set up the following equation and solve for

*a:*Plug in the value of

*a*to findbecause they’re vertical angles. Set them equal to each other, plug in the value of

*a,*and solve for*b:*124 degrees

Angles that form a linear pair add up to 180 degrees. Set the sum of

equal to 180 and solve for

*x:*Now plug in the value of

*x*to solve for