a father is four timrs as old as his son.5 years ago he was 7times as old as his son was.What is sons present age

2 answers

now:
son --- x
father -- 5x

5 years ago:
son = x-5
father = 5x-5

5x-5 = 7(x-5)

solve for x
5x-5=7(x-5)=5x-5=7x-35=-5+35=7x-5x=30/a=2x=15=15+5=20=sons age=20