Answer:
∠A = 135 and ∠B = 45
Step-by-step explanation:
Supplementary angles add up to 180
∠A = 3*∠B
∠A + ∠B = 180
3∠B + ∠B = 180
4∠B = 180
∠B = 180/4
∠B = 45
∠A = 3 *45 = 135
