6x - 7 + 9x - 8 = 90

15x - 15 = 90

15x = 105

x = 6

Complementary angles have a sum of 90 degrees.

So (6x-7)+ (9x-8)=90

6x+9x -7-8=90

Then 15x -15= 90

15x= 105

X=105/15

X=7

Hoping this helps!

well they have to add up to 90 degrees so:

6x - 7 + 9x - 8 = 90 solve