Answer:
has a right angle to hold the billboard upright. Since a triangle is 180, and there' s a right angle, then when you add angle A and angle B together, they should add up to 90.
Explanation:
A = 2B + 15
A + B = 2B+15 + B = 90
3B + 15 = 90
3B = 75, so B = 25 degrees
90 - B = A, so A = 65 degrees