SOLUTION: If Zach does a job in 9 hours And with the help of Catharine they do it together in 3 hours, How long will it take Catherine do it alone?

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Question 920222: If Zach does a job in 9 hours And with the help of Catharine they do it together in 3 hours, How long will it take Catherine do it alone?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
x long will it take Catherine do it alone
1%2F9+%2B+1%2Fx+=+1%2F3 Multiplying thru by 9x so as all denominators = 1
x + 9 = 3x
9 = 2x
9/2 = x = 4.5hr, time for Catherine do it alone