#### Answer

$y=-\frac{1}{2}x+4$

#### Work Step by Step

A linear function has the form $f(x)=ax+b$, with $a=$slope and $b=$y-intercept.
We calculate the slope from $(0,4)$ to $(8,0)$ using the graph:
slope=$\frac{0-4}{8-0}=\frac{-4}{8}=-\frac{1}{2}$
We can find the $y$-intercept by looking at the $y$ value at $x=0$:
$f(0)=4$
Therefore, the equation is: $y=-\frac{1}{2}x+4$