Question: You have a square yard with a side length of x+5. There is a square brick covered patio in the yard with a side length of x. What is the area of the uncovered portion of the yard?
The area of the yard is \displaystyle \begin{align*} (x + 5)^2 \end{align*}. Of that, \displaystyle \begin{align*} x^2 \end{align*} is covered by bricks.
The uncovered part is therefore \displaystyle \begin{align*} (x + 5)^2 - x^2 \end{align*}. Expand and simplify.