SOLUTION: A town's old street sweeper can clean the streets in 60 hours. The old sweeper together with a new sweeper can clean the streets in 15 hours. How long would ti take the new sweeper

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A town's old street sweeper can clean the streets in 60 hours. The old sweeper together with a new sweeper can clean the streets in 15 hours. How long would ti take the new sweeper      Log On


   

Question 365271: A town's old street sweeper can clean the streets in 60 hours. The old sweeper together with a new sweeper can clean the streets in 15 hours. How long would ti take the new sweeper to do the job alone?
Found 2 solutions by scott8148, mjackson73:
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
in the 15 hr working together , the old sweeper cleans 1/4 (15/60) of the streets

this means that the new sweeper cleans 3/4 of the streets in 15 hr

so it can clean 4/4 (all) the streets in ?

Answer by mjackson73(1) About Me  (Show Source):
You can put this solution on YOUR website!
60x/(60+x)=15
60x=15(60+x)
60x=900+15x
60x-15x=900
45x=900

x=900/45
x=20 hours for the new sweeper working alone.