Answer: it takes them 2.13 minutes to wash the car together.
Step-by-step explanation:
It takes Tom 3 minutes to wash a car. This means that the rate at which Tom washes the car per minute is 1/3
It takes Jerry 6.7 minutes to wash the same car. This means that the rate at which Jerry washes the car per minute is 1/6.7
If they work together, they would work simultaneously and their individual rates are additive. This means that their combined working rate would be
1/3 + 1/6.7 = 9.7/20.1
Assuming it takes t hours for both of them to clean the room working together, the working rate per hour would be 1/t. Therefore,
9.7/20.1 = 1/t
t = 20.7/9.7
t = 2.13 minutes
