Answer:
y = 4x
Step-by-step explanation:
You just have to know the relationship of the perimeter with the side length.
If the side length is x, the perimeter would be P = 2x + 2x = 4x
so if the perimeter is y, then y = 4x
y = 4x is the equation of the line.
One at a time, plug in the x values until you find one that gives the right y value.