Question 2
You need to convert your equation to form y=ax+b:

{{{(1/6)*x+4/3=-(1/2)*y}}}


{{{-(2/6)*x-2*4/3=y}}}

{{{y=-(2/6)*x-2*4/3}}}

to simplify


{{{y=-(1/3)*x-2&2/3}}}

the slope is -1/3