SOLUTION: The office jet printer can copy Maria's dissertation in 14 minutes. The laser jet printer can copy the same document in 12 minutes. If the two machines work together how long woul

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Question 261059: The office jet printer can copy Maria's dissertation in 14 minutes. The laser jet printer can copy the same document in 12 minutes. If the two machines work together how long would they take to copy the dissertation.
I thought that I should do this:
Office Jet = 1/14
Laser Jet = 1/12
1/14+1/12, but the result is 13/84 of a minute, I know this is not correct, can someone help me to find the correct formula please?

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


You are soooo close. If printer A can do the whole job in 14 minutes, then it can do 1/14 of the job in 1 minute. Likewise printer B can do 1/12 of the job in 1 minute. So when you add 1/14 of the job to 1/12 of the job, you get that both machines working together can do 13/84 of the job in one minute, therefore they can go the whole job in 84/13 minutes, just under 6 and a half minutes.


John