Answer: y = -4/3x
Explanation:
The missing numbers are the slope. An easy way to find the slope when you have the line, is to find two points on a line. In this case, I used (0,0) and (3,4). Take the number it takes to walk up from the bottom point to the y level of the top point. Place that on the top of the fraction. Then take the number it takes to walk to the side to the x level of the other point. Place that on the bottom of the fraction.
Thus we have, y = -4/3x