word problem

Question

martha can rake the leaves in her yard in 4hours. her younger brother can do the job in 7 hours. How long will it take them to do the job together

Answer 1

Hi Carolyn,

 

Since Martha can rake the yard in 4 hours, her rate is 1 yard in 4 hours or 1/4 yds/hr. Her brothers rate is 1/7 yds/hr. So the total amount raked is: 

 

Area = 1/4*t + 1/7*t

 

For just 1 yard, the equation becomes

 

1 = 1/4*t + 1/7*t

 

Now just solve for t