Answer:
Equation to solve for "x": 90 + x + x + 18 = 180
x = 36
Step-by-step explanation:
90 + x + x + 18 = 180
90 + 18 + 2x = 180
108 + 2x = 180
(108 - 108) + 2x = 180 - 108
2x = 72
2x/2 = 72/2
x = 36
90 + 36 + 36 + 18 = 180
108 + 72 = 180
180 = 180
