So you would multiply the length times width!
A complementary angle is an angle that adds up to 90 degree each and every time. So, therefore the correct formula to use is 90-63=27. Now, you have your answer and can check it twice if you'd like by the formula. Again your answer is 27.
Your answer is alredy in order
The incorrect answer is B.
All you have to do is plug in x to the formulas and see if the are equal.
4x - 2 = 3x + 6
4(8) - 2 = 3(8) + 6
30 = 30
CORRECT
The second is not only not equal, but it is the wrong kind of formula for what you are trying to prove there.
Hope that helps!