SOLUTION: frank can complete a job in 5 hours. Joe can do it in 8 hours. After frank has worked for 2 hours, Joe was asked to help Frank complete the job. In how many hours after Joe has sta

Algebra ->  Rate-of-work-word-problems -> SOLUTION: frank can complete a job in 5 hours. Joe can do it in 8 hours. After frank has worked for 2 hours, Joe was asked to help Frank complete the job. In how many hours after Joe has sta      Log On


   

Question 902560: frank can complete a job in 5 hours. Joe can do it in 8 hours. After frank has worked for 2 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 josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
Frank and Joe, in their combination of times, are doing 1 whole job.
Let t = time that Joe worked.

highlight_green%28%281%2F5%29%2A2%2B%281%2F5%2B1%2F8%29t=1%29
If you can understand the equation, that is great. Otherwise, that is what help you need.

Just solve for t.