SOLUTION: one printing machine works twice as fast as another. When both machines are used, they can print a magazine in 3 hrs. How many hours would each machine require to do the job alone?

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Question 744030: one printing machine works twice as fast as another. When both machines are used, they can print a magazine in 3 hrs. How many hours would each machine require to do the job alone?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of printing
Let +r+ = the slower machine's rate of printing
+2r+ = the faster machine's rate of printing
When both machines are used, their rate of printing is
( 1 magazine ) / ( 3 hrs )
---------------------
+r+%2B+2r+=+1%2F3+
+3r+=+1%2F3+
+r+=+1%2F9+
+2r+=+2%2F9+
+2r+=+1%2F4.5+
The fast machine can print a magazine in 4.5 hrs
The slow machine can print a magazine in 9 hrs