How do you simplify #\frac{a-3}{7}\cdot \frac{21}{3-a}#?

1 Answer
Jan 18, 2018

-3

Explanation:

#(a-3)/7*21/(3-a)#
First of all take minus common from 3-a
= #[a-3]/7*21/-(a-3)#
Now simplify by dividing
= #(1cancel(a-3))/(cancel7)*(3cancel21)/-(cancel(a-3))#
Now you are left with three in the numerator and -1 in the denominator.
= #3/-1#
Shift the negative sign to the numerator,
You get -3