Given: ∠A and ∠B are supplementary. m∠B = 7m∠A - 20 Prove: m∠A = 25, m∠B = 155 Statement Reason ∠A and ∠B are supplementary m∠A + m∠B = 180 m∠B = 7m∠A – 20 m∠A + 7m∠A – 20 =180 8m∠A – 20 = 180 8m∠A = 200 m∠A = 25 m∠B = 7(25) – 20 m∠B = 155​