Answer :

5 notebooks cost $5.25

This is a unit rate question, where the amount of money it costs is divided by the amount of items that are bought.

So 5.25 is divided by 5.

You should get a number that is the cost of one notebook.

Than multiply that number by 3 and you should get your answer.
5.25

=5+1/4

=20/4+1/4

=21/4

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(21/4)/(5/1)

=(21/4)*(1/5)

=21/20

=20/20+1/20

=1+0.05

=1.05

*One note book costs $1.05

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3 note books cost:

3*$1.05

=$3.15