A wire is first bent into the shape of a rectangle with width 3cm and length 11cm. Then the wire is unbent and reshaped into a square. What is the length of a side of the square?

The wire that makes rectangle have the same length with the wire that makes square. The length of the wire is the perimeter of rectangle, and is the perimeter of square. So the perimeter of rectangle is equal to the perimeter of square.

The equation would be

perimeter of square = perimeter of rectangle

4s = 2l + 2w

s stands for the side of square, l stands for the length of the rectangle, w stands for the width of rectangle

Input the number to the equation to find the value of s

4s = 2l + 2w

4s = 2 (3) + 2 (11)

4s = 6 + 22

4s = 28

s = 28/4

s = 7

The side of the square equals 7 cm