SOLUTION: If Sally can paint a house in 4 hours and John can pain the same house in 6 hour, how long will it take for both of them to paint the house together?

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Question 152129: If Sally can paint a house in 4 hours and John can pain the same house in 6 hour, how long will it take for both of them to paint the house together?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
If Sally can paint a house in 4 hours and John can pain the same house in 6 hour, how long will it take for both of them to paint the house together?
:
Let t = time required when they work together
;
Let the completed job = 1
:
We want to find out what fraction of the job each will do, has to add up to 1
t%2F4 + t%2F6 = 1
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Multiply equation by 12 to get rid of the denominators
12*t%2F4 + 12*t%2F6 = 12(1)
;
Cancel the denominators and you have;
3t + 2t = 12
;
5t = 12
t = 12%2F5
t = 2.4 hrs working together
:
:
Check solution on a calc: enter (2.4/4) + (2.4/6) = 1