SOLUTION: Joy can do a job in 7 hours, while it takes Lucy only 5 hours to do same job. How long will it take them to do the same job if they work together?

Question 989005: Joy can do a job in 7 hours, while it takes Lucy only 5 hours to do same job. How long will it take them to do the same job if they work together?

Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Joy can do a job in 7 hours, while it takes Lucy only 5 hours to do same job.
How long will it take them to do the same job if they work together?
:
let t = time required when working together
let the completed job = 1
:
A shared work equation, each will do a fraction of the job, the two fractions add up to one
+ = 1
multiply by the least common factor of 7 and 5, 35:
35* + 35* = 35
Cancel the denominators
5t + 7t = 35
12t = 35
t = 35/12
t = 2 hrs which is 2 + *60 = 2 hrs 55 min
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