Question

So what do I do?? Like I can graph but there only one number

Answer 1

The fact that there is only one number is okay, just continue the way you usually would.

For example find two points:

when x=0: y=-3(0), y=0

when x=2: y=-3(2), y=-6

(0,0) and (2,-6) are two points on the line. Connect them and extend the line.