Respuesta :

The rule for angles in a triangle is that they all need to add up to 180°, so you can make the three expressions equal 180 and solve:

x + 10 + x + 2 + 9x - 8 = 180
11x + 4 = 180
- 4
11x = 176
÷ 11
x = 16

So your answer is 16
I hope this helps!