Answer
$\dfrac{7}{2}$
Work Step by Step
Using the definition of the summation symbol, $\displaystyle\sum_{i=0}^6 \dfrac{i-2}{2}
$ evaluates to
\begin{array}{l}
\dfrac{0-2}{2}+\dfrac{1-2}{2}+\dfrac{2-2}{2}+\dfrac{3-2}{2}+\dfrac{4-2}{2}+\dfrac{5-2}{2}+\dfrac{6-2}{2}
\\\\=
-1+\dfrac{-1}{2}+0+\dfrac{1}{2}+1+\dfrac{3}{2}+2
\\\\=
\dfrac{7}{2}
.\end{array}
