word problem working together

Question

Jade and Jared take turns washing their parent’s car. Jared can wash the entire car in 24 minutes. It takes Jade 12 minutes to wash the same car. If they decide to work together, how long will it take them to wash the cars?

Answer 1

Think about the rate at which they can each wash the car.

 

Jared can wash the entire car in 24 minutes, so he washes 1/24 of a car in 1 minute.

 

Jade washes 1/12 of a car in one minute.

 

So together, in one minute they can wash 1/24 + 1/12 of a car.  If you add those fractions you get 1/24 + 1/12 = 1/24 + 2/24 = 3/24 = 1/8.

 

So together they can wash 1/8 of a car in one minute, so that means it will take them 8 minutes to wash the car together.