### Home > GC > Chapter 8 > Lesson 8.3.3 > Problem 8-113

8-113.

For each diagram below, write and solve an equation to find

*x*. Homework Help ✎

The sum of the interior angles = 180°(*n* − 2)

Subtract the value of the known angles (125°, 125°, and 90°) from the sum of the interior angles you found in step 1. Afterwards, divide by 2 to solve for *x*.

Note that 6*x* + 18° and the angle across from it are vertical angles, while that same angle and 2*x* + 30° are corresponding angles.

What does that mean about 6*x* + 18° and 2*x* + 30°?

*x* = 3