Question 1154714
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Howard and Edward, working together, can complete a job in 12 hours. Edward requires 18 hours to do this job alone. 
Howard and Edward start the job. After they worked for 4 hours, Howard left the job. How many hours will Edward 
require to finish the job working alone?
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        The solution in the post by @mananth is incorrect.

        Below is my correct solution.



Edward requires 18 hours to do this job alone.


He does 1/18 of job in 1 hour


Howard and Edward start the job they worked for 4 hours,


They can complete the job in 12 hours


So they can do 1/12 of the job in 1 hour


they worked for 4 hours


so they completed 4/12 of the job = 1/3 of the job


The remaining job is 1-1/3 = 2/3 of the job


Edward does 1/18 of job in 1 hour


for 1/3 of the job he will take {{{((2/3))/((1/18))}}} hours = {{{(2*18)/3}}} = {{{36/3}}} = 12 hours.


<U>ANSWER</U>.  &nbsp;&nbsp;Edward will take 12 hours to complete the job.



Solved correctly.