Answer
$\displaystyle -\frac{1}{2}d$
Work Step by Step
A loss is something we subtract, something negative.
"a half" is written as $\displaystyle \frac{1}{2}.$
" half of d" = " $\displaystyle \frac{1}{2}$ of d " = $\displaystyle \frac{1}{2}\cdot d$
Expression:$\displaystyle \quad -\frac{1}{2}d$
