SOLUTION: Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 4 hours. How much time would it take for them to mow together?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 4 hours. How much time would it take for them to mow together?      Log On


   



Question 315857: Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 4 hours. How much time would it take for them to mow together?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
jack takes 5 hours
Marilyn - 4 hours
jack does 1/5 of job in 1 hour
Marilyn does 1/4 of job in 1 hour.
to gether they do 1/4 +1/5 of the job in 1 hour.
1/4 +1/5 = 9/20 of the job in 1 hour
together they will do the job in 20 /9 hours
= 2.2 hours