Answer:
x = 6
Explanation:
Use the exterior angle theorem, which states that the 2 opposite interior angles add up to the measure of the exterior angle.
Set up an equation:
(8x - 13) + (9x - 10) = 11x + 13
Add like terms and solve for x:
17x - 23 = 11x + 13
6x - 23 = 13
6x = 36
x = 6
So, x = 6