Hi Pamela.

The important thing is that when you are adding or subtracting rational expressions, you must make sure you first have a common denominator. In the question you sent us, there already is a common denominator of w - 4, so you can simply add the numerators and simplify.

The numerator in the final expression doesn't factor, so this is in simplest form now.

Cheers,
Stephen La Rocque.