Answer
$-\frac{3}{4}$
Work Step by Step
Convert both of the numbers to improper fractions.
$7\frac{3}{4}$ = $\frac{31}{4}$, $8\frac{1}{2}$ = $\frac{17}{2}$
Convert both of them to the same denominator.
$\frac{17}{2}$ = $\frac{17\times2}{2\times2}$ = $\frac{34}{4}$
Adding a negative is the same as subtracting a positive.
$\frac{31}{4} - \frac{34}{4}$ = $-\frac{3}{4}$