The perimeter of the square below can be described by the expression 64 + 12y.

A square.

Which of the expressions describes the length of one side of the square?

A square has 4 equal sides.

64/4 = 16; 12 y/4 = 3 y
16 + 12y
4 + 12y
4 + 3y
16 + 3y