Hello!
To find the answer, we will multiply the probabilities of both cars needing oil change, and tire rotation and oil change.
3/5 need an oil change.4/7 of the 3/5 need the tire rotation. We multiply these two numbers giving us 12/35, which is our answer.
There is a 12/35 chance that a car the comes in will both an oil change and a tire rotation.
Hope this helped!