# How do you combine #3/(b-3)-b/(b-3)#?

##### 3 Answers

When you have the sum or subtraction of two fraction with the same denominator you simply mantain that denominator and sum/subtract the numerators:

I changed the sign by collecting

When you have a sum or subtraction of fractions that share the same denominator, you can simply add/subtract the numerators, as follows:

Note that the numerator and the denominator are opposite, that is, one is the negative version of the other:

and

Thus, we can either rewrite it as

or

So, the final and shortest answer for your subtraction is