Recall that the slope intercept of a line equation is
y = mx+b
where m is the slope and b is the y-intercept. Given the line equations, we should operate both sides of it, so we end up having the y term on one side on its own.
First, we start with the equation

By adding (1/2)x on both sides, we get

which is the slope-intercept form of this line equation.
On the other side, we have the equation

First, we start by adding 3y on both sides, so we get

Then, we subtract 8 on both sides, so we have

Finally, we divide both sides by 3, so we get

which is the slope intercept form of the second line equation.