∠A and ∠ B ∠B are complementary angles. If m ∠ A = ( 2 x + 10 ) ∘ ∠A=(2x+10) ∘ and m ∠ B = ( 3 x + 15 ) ∘ ∠B=(3x+15) ∘ , then find the measure of ∠ B ∠B