How do you evaluate #-\frac{18\times z}{207\times z}#?

1 Answer
Oct 21, 2017

#-2/23#

Explanation:

By evaluating or I assume simplifying the fraction, we can first cancel out the #z# since #z/z=1#

#(-18*z)/(207*z)= -18/207#

Remember you can only do this since the #z# is multiplied to both the numerator and denominator. If it was added to the numerator and denominator, then we could not do this since canceling out #z# is really just dividing it by itself, and we can only do this without distribution to multiplied/divided terms.

Now we simplify #-18/207#

We know 18 is divisible by 9 but what about 207? The divisibility rule for 9 is that if the sum of the digits is divisible by 9, then the number is divisible by 9.

The digits in 207 are 2, 0, and 7.

#2+0+7=9# and 9 is divisible by 9.

This means 207 is divisible by 9. So:

#-18/207=(-18/9)/(207/9)=-2/23#

Simplified, the fraction is #-2/23#

I hope this helps you out!