# Word problem about multiplying and subtracting fractions

by Moises Villalpando
(San Diego, CA)

Your job is to sweep 3/4 of the school's cafeteria. Your friend agrees to help you and sweeps 1/3 of your part. What fraction of the entire floor your friend agreed to sweep? What fraction of the entire cafeteria floor you will have to sweep?

Solution:

1/3 times 3/4 = 3/12 = 1/4

So, your friend will complete 1/4 of the job.

Your part now is 3/4 - 1/4 = 2/4 = 1/2

You will sweep only half the cafeteria.

Alternatively, you could write 3/4 = 1/4 + 1/4 + 1/4

and then argue that you have 3 jobs to do consisted of 1/4, 1/4, and 1/4.

If your friend takes 1 out of these 3 jobs, it means 1/4.

Then, you are left with 1/4 + 1/4, which is equal to 2/4 or 1/2

Average Rating

 Dec 04, 2012 Rating Very helpful by: Anonymous This was an excellet example to help my daughter understand her math problem!

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