SOLUTION: Martha can rake the leaves in her yard in 4 hours. her younger brother can do the job in 6 hours. How long will it take them to do the job if they work together?

Question 978129: Martha can rake the leaves in her yard in 4 hours. her younger brother can do the job in 6 hours. How long will it take them to do the job if they work together?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Martha can rake the leaves in her yard in 4 hours.
her younger brother can do the job in 6 hours.
How long will it take them to do the job if they work together?
:
Let t = time required when they work together
let the completed job = 1
:
Each will do a fraction of the job, the sum of the fractions = 1
+ = 1
multiply equation by the least common multiple of the denominators, 12.
12* + 12* = 12(1)
Cancel the denominators, and you have
3t + 2t = 12
5t = 12
t = 12/5
t = 2.4 hrs working together which is; 2 + .4(60) = 2 hrs 24 min
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