6) \(\frac{a}{2x}-\frac{a+b}{2x}=\)

\(\frac{a}{2x}-\frac{a+b}{2x}=\frac{a-(a+b)}{2x}=\frac{a-a-b}{2x}=\frac{-b}{2x}\).

Ответ: \(\frac{-b}{2x}\)