It takes my Father 3 hours to plow the our cornfield with his new tractor.
Using the old tractor it takes me 5 hours.
If we both plow for 1 hour before I go to school,how long will it take him to finish
:
let t = time Dad plows after he goes to school
:
Let the completed job = 1; (a plowed field)
:
A shared work equation
%28%28t%2B1%29%29%2F3 + 1%2F5 = 1
Multiply by 15, results
5(t+1) + 3 = 15
5t + 5 + 3 = 15
5t = 15 - 8
t = 7%2F5
ANSWER
t = 1.4 hrs or 1 + .4(60) = 1 hr 24 more minutes to finish
hope this helps :)