In a geometric diagram, ∠A and ∠B are complementary, and they form a straight line with ∠C. If m∠A=x°, m∠B=(2x)°, and m∠C=90°, what is the measure of ∠B?

A. 60
B. 90
C. 180
D. 30

1 answer

Since ∠A and ∠B are complementary, we have x + 2x = 90.

Combining like terms, we get 3x = 90.

Dividing both sides by 3, we get x = 30.

Therefore, the measure of ∠B is 2x = 2(30) = <<2*30=60>>60°.

The answer is A. 60.