# How do you combine ( x +1 )/ 2 - (w/2)?

Since $\frac{x + 1}{2}$ and $\frac{w}{2}$ have the same denominator:
$\textcolor{w h i t e}{\text{XXXX}}$$\left(\frac{x + 1}{2}\right) - \left(\frac{w}{2}\right)$
$\textcolor{w h i t e}{\text{XXXX}}$$\textcolor{w h i t e}{\text{XXXX}}$$= \frac{x + 1 - w}{2}$