Suppose a and b are complementary angles, m a =(3x+5) and m b= (2x-15). solve for x and then find m a and m b

2 angles are complementary if the sum of their measures is 90°.

For example  if m(P) = 41°  and m(Q)=49°, then P and Q are complementary.

Thus A and B are complementary means that m(A)=m(B)=90°:

(3x+5°) + (2x-15°) =90°

5x-10°=90°

5x=100°

x=20°

Thus 

m(A)=3x+5°=3* 20°+5°=60°+5°=65°

m(B)=2x-15°=2*20°-15°=40°-15°=25°

What exactly is your question?