Question

In the above figure, m∠A = 30° and m∠B = (2x + 10)°. If angles A and B are complementary angles, what are the value of x and the measure of angle B?

A.
x = 55, m∠B = 60°
B.
x = 25, m∠B = 60°
C.
x = 70, m∠B = 150°
D.
x = 25, m∠B = 50°

Answer 1

Explanation:

option B

Complementary angles add up to 90°

m∠A + m∠B = 90

30 + 2x + 10 = 90

2x + 40 = 90

To find the value of x, we have to isolate x. To isolate x, first we have subtract 40 from both sides.

2x = 90 -40

2x = 50

Now, divide both sides by 2

x = 50/2

x = 25°

∠B = 2x + 10

= 2*25 + 10

= 50 + 10

∠B = 60°