Question

It takes a man 3 hours to wash and wax the family car. If his teenage son helps him, it only takes one hour. How long will it take the son, working alone to wash and wax the car?

Answer 1

Answer:the son working alone will take 1¹/₂ hours

Explanation:

Step 1

let x represent the hours that the son needs to wash and wax the car alone thus his rate is 1/x cars per hour

While

the rate of the father is 1/3 cars per hour , working together rate is 1/1 cars per hour.

Step 2

Writing it mathematically, becomes

1/x + 1/3 = 1/1

Dividing through by 3x so all denominations can be rqual to 1 , we have

3 + x = 3x

3= 3x-x

3= 2x

x= 3/2

Therefore the son working alone will take 1¹/₂ hours