Answer:
y/x
Step-by-step explanation:
The constant of proportionality defines two directly proportional quantities that decrease or increase proportionally/same rate.
Given constant of proportionality= k
Side of the square= x
Perimeter of the square= y
constant of proportionality=k=y/x
For example if perimeter of square is 8 and side of square is 2, constant of proportionality is 8/2=4