Answer:
The angles are complementary; X = 15
Explanation:
When angles are complementary, they always add up to 90 degrees angles, which is a right angle. Supplementary angles add up to 180 degree angles, which is a straight line. When telling the difference, my math teacher taught me to remember the saying "complementing is always the right thing to do" (it's corny, I know, but it worked for me lol)
To find x, you would do 90 minus the other angle, which is 45, to get 45. Then, you would divide by 3, to get 15 as x.