Question

In parallelogram ABCDABCD, ∠A∠A and ∠B∠B are adjacent. The measure of ∠B∠B is two times the measure of ∠A∠A. Which equation gives the exact measure of ∠A∠A?

Answer 1

Since adjacent angles in a parallelogram are supplementary (they add up to 180°), and ∠B is double as ∠A, you have this equation:

∠A + 2·∠A = 180°

From that you can find: 3·∠A = 180° ⇒ ∠A = 60°.