Hello from MrBillDoesMath!
Answer: 22.5
Discussion:
An angle and its complement add up to 90 degrees So, if "@" is the angle mentioned in the question, its complement is (90 -@). Per the question
@ = (1/3) (90 - @)
Multiply both sides by 3 to get
3@ = 90 - @
Add @ to each side
4@ = 90
Divide each side by 4
@ = 90/4 = 22.5
(and the complementary angle is 67.5)
Regards, MrB