SOLUTION: 18 persons can wash 50 cars in 4 hours. How long will it take 22 persons wash 48 cars ? Thanks for helping me *smile face*

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Question 961624: 18 persons can wash 50 cars in 4 hours. How long will it take 22 persons wash 48 cars ?
Thanks for helping me *smile face*
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
This is uniform work-rates type of problem.

Let r be rate of washing cars for 1 person in unit of car per hour.

RT=J rate time job, and "job" means whatever amount of CARS.

system%2818r%2A4=50%2C22%2Ar%2At=48%29.
Note this system uses two unknown variables and is of two equations. One of the equations has just the variable, r, and that is the equation you use first; and then substitute this into the other equation and finish solving for t.