Answer
a=-5
Work Step by Step
When a linear equation is written in slope-intercept form, or y=mx+b form, m=slope and b=y-intercept.
The equation y=-$\frac{1}{2}$ax-5 is written in y=mx+b form and has a slope of $\frac{-1}{2}$a
Since m= $\frac{5}{2}$, we can solve for a now that we know m=$\frac{-1}{2}$a because if
m=$\frac{5}{2}$, and
m=$\frac{-1}{2}$a, then
$\frac{5}{2}$=$\frac{-1}{2}$a
Now, to solve for a, we multiply by -2 on both sides
(-2)$\frac{5}{2}$=(-2)$\frac{-1a}{2}$
a=-5
