Question

it takes a man 5 hours to wash and wax the family car. if his teenage son helps him it only take one hour. how long would it take the son working alone to washa nd wax the car

Answer 1

1.25 hours

Explanation:

the man takes 5 hours to wash it and so in one hour, he washes 0.2 of the car.

man + son = 1 hour, so the son does 1-0.2=0.8 of the car in 1 hour.

thus, he would take 1/0.8=1.25 hours