m∠ABD=87 ∘ m, angle, A, B, D, equals, 87, degrees \qquad m \angle ABC = 9x - 1^\circm∠ABC=9x−1 ∘ m, angle, A, B, C, equals, 9, x, minus, 1, degrees \qquad m \angle CBD = 6x + 58^\circm∠CBD=6x+58 ∘ m, angle, C, B, D, equals, 6, x, plus, 58, degrees Find m\angle ABCm∠ABCm, angle, A, B, C:
