Ms. Henry is 36 years old. How old was she x years ago?

A)36x
B)x-36
C)36-x
D)36+x

The answer is C, 36-x. Try this with your own age. If you are 15, how old were you x years ago? If x is 3, then the answer is 12, or 15-3. If x is 5, the answer is 10, or 15-5.