Answers

2014-12-29T22:56:46+05:30
Sally can paint the house in 4 hours
The rate at which he  can paint the house is 1/4 per hour
John can paint the house in 5 hours
                       The rate is 1/5 hours
Together the rate is 1/4+1/5=9/20
So they can paint the house in 1/(9/20)=20/9 hours =2.22hrs
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