Answer:
A. 30 degrees
Explanation:
Set the two angles equal to each other:
3x-15 = 45-x
Solve for x:
4x -15 = 45
4x = 60
x = 15
Finally, plug in the x to one of the equations (preferably 45 - x since it's easier to solve) and solve for x.
45 - 15 = 30