Answer:
15 minutes
Step-by-step explanation:
Let the minutes spent washing a car =x
• Total minutes spent washing 5 cars = 5x
,
• Also, Sharon spent 15 minutes putting everything away.
Since it took her a total of 90 minutes, we have that:

We then solve the equation for x.
5x=90-15
5x=75
x=75/5
x=15
It took Sharon 15 minutes to wash each car.