∠A=5x−18 ∘ start color #11accd, angle, A, equals, 5, x, minus, 18, degrees, end color #11accd \qquad \green{\angle B=3x + 42^\circ}∠B=3x+42 ∘ start color #28ae7b, angle, B, equals, 3, x, plus, 42, degrees, end color #28ae7b Solve for xxx and then find the measure of \blueD{\angle A}∠Astart color #11accd, angle, A, end color #11accd: