Question

Norton can mow the large lawn in about 5 hours. When he works with

Jesse, they can mow the same lawn together in about 3 hours. Which of
the following equations can be used to determine how long it would
take Jesse to mow the lawn by himself?
total. jobs
job. A
time. together time time
job. B

Answer 1

7.5 hours

Explanation:

The key here is to find out how much can be done in the same amount ot time

the least common multiple of 5 hrs and 3 hrs is 15hrs

In 15 hours:

- At 5 hours per lawn Norton could mow 15/5 = 3 lawns

- At 3 hours per lawn together thay could mow 15/3 = 5 lawns

In 15 hours Jesse would mow 5 - 3 = 2 lawns

15 hours/ 2 lawns = 7.5 hours per lawn

7.5 hours

--------------------

Here's the math

1 lawn/5hrs + x = 1 lawn / 3hrs

1/5 + x = 1/3

Subtract 1/5 from both sides

x = 1/3 - 1/5

x = 5/15 - 3/15

x = 2/15

x = 2lawns/15 hrs

15hrs/2lawns = 7.5 hrs per lawn

7.5 hours