Solving
Knowing that we have the information needed we will first find the perimeter of the rectangle.
Rectangle:
Length: 13cm
Width: 7cm
Formula: L+L+W+W
13+13+7+7 = 40cm
Meaning the perimeter is 40cm and we can use this to find the length of a square. From general knowledge we know that all sides of a square is equal.
So if we divide the 4 sides by 40 we will get our answer.
40 ÷ 4 = 10
So B would be our answer...
Statement
Therefore the length of a side of the square is 10cm, meaning answer B is correct.