Word Problem on Work Done by Two People

Topic : Word problem

Question : Jethro can mow 5 lawnsin 4 hours while Otis can mow 5 lawns in 6 hours. How long will it take to mow 5 lawns together?

Solution :
Time taken by Jethro = 4 hrs
Jethro's one hour work = 1/4
Time taken by Otis = 6 hrs
Otis' one hour work = 1/6
Jethro's and Otis' work 1/4 + 1/6
= (1/4*3/3) + (1/6 *2/2)
= 3+2/12
= 5/12
Time taken together = 12/5 = 2.2hrs