SOLUTION: Frank can complete a job in 5 hours. Joe can do it in 8 hours. After Frank had worked for two hours, Joe was asked to help Frank complete the job. In how many hours after Joe has s

Question 155233: Frank can complete a job in 5 hours. Joe can do it in 8 hours. After Frank had worked for two hours, Joe was asked to help Frank complete the job. In how many hours after Joe has started will they complete the job?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Frank can complete a job in 5 hours. Joe can do it in 8 hours. After Frank had worked for two hours, Joe was asked to help Frank complete the job. In how many hours after Joe has started will they complete the job?
:
let t = hrs that Joe and Frank worked together to complete the job
:
Let the completed job = 1
:
Frank will work a total of (t+2) hrs
:
A typical shared work equation:
+ = 1
Get rid of the denominators by mult by 40, resultis:
8(t+2) + 5t = 40
8t + 16 + 5t = 40
13t = 40 - 16
t =
t = 1.846 hrs they worked together to complete the job
:
:
Check solution on calc. (Frank worked 1.846 + 2)
(3.846/5) + 1.846/8) =
.769 + .231 = 1; confirms our solution
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