# The square of Mark's age 3 years ago is 6 times the age he will be in 9 years. What is his age now?

##### 1 Answer

Mar 16, 2018

15 years old

#### Explanation:

If we denote Mark's age today by

We know that

Thus by multiplying

Which, when simplified, leads us to a quadratic equation:

Hence the two possible answers are:

Obviously, you cannot be -3 years old, so he must be 15 years old.