How do you evaluate #15\div \frac{7}{5}#?

2 Answers
Oct 13, 2017

#75/7#

Explanation:

When you divide by a number, you can also think of it as multiplying by its reciprocal. For example:

#6*1/2=3#

The reciprocal of #1/2# is #2#. So:

#6-:2=3#

With this idea in mind, we can rewrite

#15-:7/5#

as

#15*5/7#

#=75/7 = 10+5/7#

Oct 13, 2017

Change division to multiplication by the reciprocal, multiply fractions across.

Explanation:

Dividing by a fraction is the same thing as multiplying by its reciprocal (numerator and denominator switch).

We can express this as 15 times #5/7#, and for the sake of simplicity, we can write 15 as #15/1#.

#15/1# * #5/7# = #75/7#

We can change #75/7# to a mixed number by the following:

  • 7 goes into 75 10 times . 10 will be the whole number
  • 7 times 10 is 5 short of 75, so 5 will be the numerator
  • The denominator stays the same, 7

Final answer: #75/7# or 10#5/7#