Given: m∠A + m∠B = 90° (Definition of Complementary Angles).
Given: m∠B = (5x + 8)°
A) m∠A = 180° + (5x + 8) is your answer choice:
Why it isn't the others:
B) m∠A = 90° - (5x + 8)
You are solving for complementary angles (90° in total when combined), so you subtract the measurement for B (5x + 8) to get A.
C) m∠A = 180° - 2(5x + 8)°
You double the complementary angle to solve for the supplementary. Essentially, just divide this answer by two to get the complementary angles.
D) m∠A = 82 - 5x
I was confused by this one, but essentially they just did one step of the isolating the variable, which was subtracting 8 from both sides. They did not finish isolating the variable however.
