I really don't know where to go with this. I just need help with it fast. because idk what I'm doing I'm giving max points.

This is what i would put Because they have given you slope and y intercept .
Equation of line format
Y=mx+b
Where slope is "m" : -1/2
Where Y-intercept is "b": 12
Therefore,
Y= -1/2x+12