Lets consider the side of square be 'x' units
So as per data,
Length of rectangle is x+5
Breadth of rectangle is x/2
and also as per data, the areas of rectangle and square are equal.
Area of rectangle = Length * Breadth = (x+5)*x/2 = 

 <- equation1
Area of square = Side* Side= x*x = 

 <- equation2
As per given data, Equation1 and equation 2 are equal
so 

 = tex] x^{2} [/tex] 



x = 5
So the side of square = 5 units 
For Square, both dimensions are equal.