which two equations can be used to determine the measure of these two angles?

Question

angle 1: 4x
angle 2: 7x-9
it has a box so the angle is complementary.

a. (7x-9) -4x=90
b. (7x-9)+4x=180
c. (7x-9) +4x=90
d. 11x-9=90
e. 3x-9=90
f. 11x-9=180

Answer 1

a. (7x-9) -4x=90
c. (7x-9) +4x=90