SOLUTION: A towns old street sweeper can clean the streets in 60h. The old sweeper together with the new sweeper can clean the street in 15h. How long would it take the new one to do the jo

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: A towns old street sweeper can clean the streets in 60h. The old sweeper together with the new sweeper can clean the street in 15h. How long would it take the new one to do the jo      Log On


   



Question 546739: A towns old street sweeper can clean the streets in 60h. The old sweeper together with the new sweeper can clean the street in 15h. How long would it take the new one to do the job alone?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A towns old street sweeper can clean the streets in 60h. The old sweeper together with the new sweeper can clean the street in 15h. How long would it take the new one to do the job alone?
:
Let n = new sweeper's time working alone
Let a completed job = 1 (a swept street)
:
15%2F60 + 15%2Fn = 1
Reduce the fraction
1%2F4 + 15%2Fn = 1
mult by 4n
n + 4(15) = 4n
60 = 4n - n
60 = 3n
n = 60/3
n = 20 hrs