Answer
$\dfrac{a+1}{2}-\dfrac{a-1}{2}=1$
Work Step by Step
$\dfrac{a+1}{2}-\dfrac{a-1}{2}$
Since the two rational expressions have the same denominator, evaluate the subtraction of the numerators and use the same denominator in the resulting expression:
$\dfrac{a+1}{2}-\dfrac{a-1}{2}=\dfrac{a+1-(a-1)}{2}=...$
Simplify:
$...=\dfrac{a+1-a+1}{2}=\dfrac{1+1}{2}=\dfrac{2}{2}=1$