SOLUTION: Mary can paint her apartment in 5 hours. Jim can paint it in 7 hours. If they work together, how long will it take to paint Mary's apartment?

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Question 547344: Mary can paint her apartment in 5 hours. Jim can paint it in 7 hours. If they work together, how long will it take to paint Mary's apartment?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
add their rates of painting
Mary's rate:
( 1 apt ) / ( 5 hrs )
Jim's rate:
{ 1 apt. ) / ( 7 hrs )
Working together:
( 1 apt. ) / ( x hrs )
----------------
+1%2F5+%2B+1%2F7+=+1%2Fx+
Multiply both sides by +35x+
+7x+%2B+5x+=+35+
+12x+=+35+
+x+=+35%2F12+
This is 2 and 11/12
+11%2F12%2A60+=+55+
It will take them 2 hrs and 55 min working together