Posted by jj on Monday, May 3, 2010 at 10:46pm.
Bob mosw his lawn in 3 hours, Jane can mow the same lawn in 5 hours. How much time would it take for them to mow the lawn together?

algebra  MathMate, Monday, May 3, 2010 at 11:26pm
This is a problem in which you need to convert the work rate into something addable.
If Bob does his lawn in 3 hours, he does 1/3 in one hour. Similarly Jane can mow 1/5 of the lawn in one hour.
So in one hour, both working together will mow (1/3)+(1/5)=8/15 of the lawn.
The time it takes to mow the complete lawn is therefore 1/(8/15)=15/8=1 7/8 hours. 
algebra  jj, Tuesday, May 4, 2010 at 12:11am
Thank you so much!

algebra :)  MathMate, Tuesday, May 4, 2010 at 8:51am
You're welcome!