Question

Five years hence, the age of Jacob will be three times that of his son. Five years ago, Jacob's age was seven times of his son. What are their present ages?

Answer 1

Let 'x' be the present age of jacob and 'y' be the age of his son

As per question

$x+5=3(y+5).....\left(1\right)$

$x-5=7(y-5).......\left(2\right)$

Adding (1) and (2)

$2x=3y+15+7y-35$

$2x=10y-20$

$x=5y-\mathrm{10...}\left(3\right)$

Putting (3) in (1)

$5y-5=3y+15$

$2y=20$

$y=10$

Putting in (3)

$x=5\times 10-10$

$x=40$

Therefore Present age of Jacob is 40 years and his son is 10 years.