SOLUTION: Martha can rake the leaves in her yard in 5 hours. Her brother can do the job in 3 hours. How long will it take them to do the job working together? answer in fraction an hr

Question 1015897: Martha can rake the leaves in her yard in 5 hours. Her brother can do the job in 3 hours. How long will it take them to do the job working together? answer in fraction an hr

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
In an hour, Martha does 1/5 of the yard.
In an hour, her brother does 1/3 of the yard.
together, they do (1/5)+(1/3) of the yard every hour or (8/15) of the yard (adding the two with common denominator of 15).
It takes 15/8 hours for both of them to do it.
(1/5)+(1/3)=(1/x)
multiply everything by 15x
3x+5x=15
x=(15/8)
Check.
She does 20% of the yard in an hour. He does 33%. It will take between 1 and 2 hours, closer to 2.

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