x^2-y^2 over 4x+4y multiplied by x+y over x-y

This isn't a complex fraction. It's just a basic exercise in the difference of two squares.

What are you having trouble with?

\frac{x^{2}-y^{2}}{4x+4y}\cdot\frac{x+y}{x-y}

Factor 4 out of the left denominator and use the difference of two squares formula on the left numerator. Then cancel accordingly. It should simplify a great deal.