Calculus with Applications (10th Edition)

$\displaystyle \frac{1}{5}$
$y=mx+b$ is the slope intercept form: slope m and y-intercept b. So, we solve $x=5y$ for y (divide both sides by 5): $y=\displaystyle \frac{1}{5}x$ so, m=$\displaystyle \frac{1}{5}$