SOLUTION: Alan can do a piece of work in 15 days; Bill can do it in 20 days. If Alan works alone on the job for five days, and theb Bill helps hin complete it, how long does Bill work?

Question 638939: Alan can do a piece of work in 15 days; Bill can do it in 20 days. If Alan works alone on the job for five days, and theb Bill helps hin complete it, how long does Bill work?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
If Alan does a whole job in 15 days, he will do 1/3 of the job
in 5 days, so 1/3 is done when Bill starts working.
2/3 of the job is left to do.
Now add their rates of working to get their rate working together
In words:
( 1 job ) / ( 15 days ) + ( 1 job ) / ( 20 days ) = ( 2/3 of a job ) / ( x days )

Multiply both sides by

Bill works for 5.7143 days
check:

close enough
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