Answer:
x = 39
Step-by-step explanation:
let [180 - (31 + x)] = 3rd angle inside triangle; simplified is '149 - x'
the (2x - 8) angle and '149 - x' angle are supplementary, thus add to 180
2x - 8 + (149 - x) = 180
2x + (-x) + (-8) + 149 = 180
x + 141 = 180
x = 39
