A square has 4 sides.
And each of the sides are all the same length.
3/4 can become 0.75 as a decimal.
The formula for perimeter is all of the sides added up.
so we add 0.75 together 4 times.
Here's the math:)
0.75 + 0.75 + 0.75 + 0.75 = 3
So the perimeter of the square is 3 miles long.
:P