SOLUTION: A library crew can shelf books in six hours. Another crew can do the job in four hours. If the first begins and is joined by the second crew one hour later, how many hours will it

Question 759062: A library crew can shelf books in six hours. Another crew can do the job in four hours. If the first begins and is joined by the second crew one hour later, how many hours will it take to finish the job?
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
A library crew can shelf books in six hours. Another crew can do the job in four hours. If the first begins and is joined by the second crew one hour later, how many hours will it take to finish the job?
***
let x=time it takes to finish job
1/6=work rate of library crew
1/4=work rate of other crew
x/6+(x-1)/4=100% of job
x/6+(x-1)/4=1
LCD=12
2x+3(x-1)=12
2x+3x-3=12
5x=15
x=3
time it takes to finish job=3 hrs
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