How do you solve #\frac{6}{15} \div \frac{4}{21}#?

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Answer 1 · 2016-09-16T12:44:19

#6/15-:4/21=21/10#

Dividing a fraction or any number by another fraction or number means multiplying by its mulltiplicative inverse.

Multiplicative inverse of a fraction #a/b# is #b/a# and hence dividing by #a/b# means multiplying by #b/a#.

As we have to divide #6/15# by #4/21#, this means multiplying by #21/4#, hence

#6/15-:4/21=6/15xx21/4#

= #(2xx3)/(3xx5)xx(3xx7)/(2xx2)#

= #(cancel2xxcancel3)/(cancel3xx5)xx(3xx7)/(cancel2xx2)#

= #(3xx7)/(5xx2)#

= #21/10#