SOLUTION: A farmer can plow a field in 40 minutes. His son can plow the same field in 1 hour. How long would it take them to plow the field if they worked together? (Together/alone)+(Toge

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Question 1036629: A farmer can plow a field in 40 minutes. His son can plow the same field in 1 hour. How long would it take them to plow the field if they worked together?
(Together/alone)+(Together/alone)= 1 job done
*What I had so far, don't know if it's correct:
t=together
1 hour=60 minutes
(t/40 min.)+(t/60 min.)= 1 job done

Found 2 solutions by ikleyn, JBarnum:
Answer by ikleyn(52752) About Me  (Show Source):
Answer by JBarnum(2146) About Me  (Show Source):
You can put this solution on YOUR website!
Taken from a previous tutors lesson plan:
Many times, students don't know how to begin to deal with these problems. Actually, they are quite simple once you know how to set up the appropiate equation or system of equations. I'll give you now the single most important formula that will help you solve these problems.

Basic Formula

Let's assume we have two workers (pipes, machines, etc): A and B.
Worker A can finish a job in X hours when working alone.
Worker B can finish a job in Y hours when working alone
The number of minutes they need to complete the job
when they're both working at the same time is given by
Time=1%2F%281%2FX+%2B+1%2FY%29

1%2F%28%281%2F40%29%2B%281%2F60%29%29
1%2F%28%286%2F240%29%2B%284%2F240%29%29
1%2F%2810%2F240%29
1%2F%281%2F24%29
1%2824%2F1%29
highlight_green%2824%29minutes