How do you find the slope and y-intercept for the line y = 5 – 1/2x?

The slope is $- \frac{1}{2}$, the $y$-intercept is $5$.
$y = m x + q$, you automatically get that $m$ is the slope and $q$ is the $y$-intercept (the form $y = m x + q$ is indeed called "slope-intercept form").