Question

If the current age is considered as x, 13 years ago he was x-13 and in 11 years he will be x+11:

Answer 1

Therefore, Peter is 21 years old.

Explanation:

`\bf{ x+11=((x-13)^2)/(2) \ \Longrightarrow \ 2x+22=x^2-26x+169 }`

`\bf{ 0=x^2-28x+147=(x-21)(x+7) }`