Answer:
x = 15
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
Sum the 3 given angles and equate to 180
8x - 7 + x + 7 + 2x + 15 = 180 , that is
11x + 15 = 180 ( subtract 15 from both sides )
11x = 165 ( divide both sides by 11 )
x = 15
