What is a real world situation that can be represented by the equation y = 4x ?

One situation would be :

Let's say The price of a pen, lets take it as y, is 4 times that of an eraser.

And let's say the price of an eraser is x.

Therefore

Or of you prefer:

Let's say the length of one side of a square field is x.

And the perimeter of a square field is y.

perimeter of a square = 4 times the length of one side.

Thus,