the office jet printer can copy Lisa's dissertation in 12 minutes. The laser jet printer can copy the same document in 22 minutes. If the two machines work together, how long would they take to copy the dissertation?

Question

the office jet printer can copy Lisa's dissertation in 12 minutes.  The laser jet printer can copy the same document in 22 minutes.  If the two machines work together, how long would they take to copy the dissertation?

anonymous · Answer

Well let's say the dissertation is 'd' pages long.  The rate of the first printer, in pages per minute, is d/12.  The second printer is d/22.  Does that make sense so far?

anonymous · Answer

yes

anonymous · Answer

So the total speed of the printers together is d/12 + d/22

anonymous · Answer

And the amount of time it takes to print D pages at that speed is d / (d/12 + d/22).  If you work that out, the d's all cancel.

anonymous · Answer

i did that and all I came up with is 34.....I am missing a step somewhere just not sure where....I know 34 minutes is not the correct answer

anonymous · Answer

I get 132/17

anonymous · Answer

that is what I just got when I recalculated it....not sure how to break that into minutes ...if I can at all

anonymous · Answer

well you can just divide if you want a decimal answer