Question 440953
Jimmy can wash his car in 30 minutes his son can wash his car in 120 minutes working together his long will it take them to wash the car?
.
Let x = time (mins) it takes for both 
then
x(1/30 + 1/120) = 1
multiplying both sides by 120:
x(4 + 1) = 120
x(5) = 120
x = 120/5
x = 24 minutes