Question

One angle measures 19° and another angle measures (4d − 9)°. If the angles are complementary, what is the value of d?

d = 7
d = 20
d = 25
d = 42.5

Answer 1

d = 20

Explanation:

90-19 = 71

(4d-9) = 71

4d = 80

d = 20

Answer 2

d = 20

Explanation:

Complementary angles are two angles that add up to 90°.

We know that one angle is 19° and the other is (4d − 9)°. So, we can set up the equation:

19 + (4d − 9) = 90.

Solving for d, we get:

19 + (4d − 9) = 90

19 + 4d − 9 = 90

4d + 10 = 90

4d = 80

d = 20

Therefore, the value of d is 20.