Answer:
I don't know what I'm suppose to solve, but it's probably one of these.
x = 8
Angle A = 48 degrees, Angle B = 132 degrees
Explanation:
(4x + 12) + (15x - 3) = 180
19x +9 = 180
19x = 171
x = 9
Angle A: 4x + 12 --> 4(9) + 12 --> 36 + 12 --> 48
Angle B: 15x - 3 --> 15(9) - 3 --> 135 - 3 --> 132
48 + 132 = 180