SOLUTION: jim's copier can do a printing job in 7 hours. janet's copies can do the same job in 12 hours. how long would it take to do the job with both copies?

Question 889347: jim's copier can do a printing job in 7 hours. janet's copies can do the same job in 12 hours. how long would it take to do the job with both copies?
Found 2 solutions by josmiceli, LinnW:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Add their rates of printing
Jim's:
( 1 job ) / ( 7 hrs )
Janet's:
( 1 job ) / ( 12 hrs )
-------------------
Let = time in hours for
both printers to do the job

Multiply both sides by

-----------------------
It will take both copiers 4 hrs 25 min 16 sec
check answer:

Answer by LinnW(1048) (Show Source): You can put this solution on YOUR website!
Jims copier does 1/7 of a job per hour
Janets does 1/12 per hour
Set t = time to complete a job
t(1/7) + t(1/12) = 1 job
t(1/7 + 1/12) = 1
use 7*12 as a common denominator

multiply each side by
t = = 4.421 hours
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