SOLUTION: If Mary can paint a house in 4 hours and Dan can paint a house in 6 hours how long will it take them to paint a house together?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: If Mary can paint a house in 4 hours and Dan can paint a house in 6 hours how long will it take them to paint a house together?      Log On


   

Question 905076: If Mary can paint a house in 4 hours and Dan can paint a house in 6 hours how long will it take them to paint a house together?
Found 2 solutions by ewatrrr, josmiceli:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
x the time together
1%2F4+%2B+1%2F6+=+1%2Fx
3x + 2x = 12
5x = 12
x = 2.4hr, the time together

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 house ) / ( 4 hrs )
Dan's rate:
( 1 house ) / ( 6 hrs )
---------------------
Let +t+ = time in hrs to paint
the house working together
+1%2F4+%2B+1%2F6+=+1%2Ft+
Multiply both sides by +12t+
+3t+%2B+2t+=+12+
+5t+=+12+
+t+=+1.4+
+.4%2A60+=+24+
It will take them 1 hr 24 min working together