Answer: A) 55
Step-by-step explanation:
The arrow markers tell us we have two sets of parallel sides, which then tells us we have a parallelogram.
In any parallelogram, the adjacent angles add to 180. They are supplementary.
B+C = 180
(2x+15) + (x) = 180
3x+15 = 180
3x = 180-15
3x = 165
x = 165/3
x = 55 which points us to choice A as the final answer.