The product of Nisha's age 3 years ago and her age 3 years from now is 160. What is her present age?

Explanation

1. 01

   Let her present age be $x$. Then $(x - 3)(x + 3) = 160$.

2. 02

   $x^2 - 9 = 160$, so $x^2 = 169$.

3. 03

   $x = 13$ (an age cannot be negative).

4. 04

   Check: $10 \times 16 = 160$.