4. Simplify

This is a division of fractions problem. We are dividing the bottom into the top. We do that by inverting the bottom and multiplying it times the top. But, since after we invert and multiply, we are going to factor and cancel, factor everything first.

The top of the bottom fraction doesn't factor so we leave it alone. We could cancel at this point by canceling the things that would cancel if we inverted and multiplied. If we inverted and multiplied, we would get,

which simplifies to