Question

You can complete the yard work at your friend's house in 5 hours. Working together, you and your friend can complete the same yard work in 3 hours. How long would it take your friend to complete the yard work when working alone?

Answer 1

The correct answer is 7.5 hours.

You can complete it in 5 hours

And by working together it can be completed in 3 hours

So take the LCM of 5 , 3 which is 15

So total unit of work is 15.

So the total work done by you is 15/5 = 3 units per hour

You + Your Friend = 15/3 = 5 units per hour

So , 3 + Your Friend = 5

Your friend = 2 unit per hour

Total work is 15 so 15/2 means 7.5 hours.