If ∠a and ∠b are supplementary angles and m∠a = 3m∠b, find m∠a and m∠b.

∠A and ∠B are supplementary so that means they have a sum of 180°.
m ∠A=3(m ∠B) and m ∠B=?

m ∠A + m ∠B=180°
3 (m ∠B) + m ∠B=180°
4 m ∠B=180°
4/4 m ∠B=180°/4
m ∠B=45° and m ∠A=3(m ∠B)=3 (45)=135°