If the two angles are complementary, find the measure of each of angle. I am having trouble decoding this problem in it it says 7f and 2f what is the formula for this problem

Answer:
f=10
Step-by-step explanation:
I don't know a formula for this but I can see that <CRE is a 90° angle so 7f+2f=90 and if f=10 7f=70 and 2f=20 which fits