Given that the triangle in the picture is a right triangle, then ∠A and ∠B are complementary, that is,
m∠A + m∠B = 90°
Replacing with data, and solving for x,
(3x + 3) + (5x + 7) = 90
(3x + 5x) + (3 + 7) = 90
8x + 10 = 90
8x = 90 - 10
8x = 80
x = 80/8
x = 10
Therefore,
m∠A = 3x + 3 = 3(10) + 3 = 33°
m∠B = 5x + 7 = 5(10) + 7 = 57°
