Hi,
If 5in is added to the width of the rectangle , a square with perimeter 36in is Obtained.
Square has sides = 9in , width
of rectangle: w+5= 9, w = 4in
Question states*** Original Rectangle had a P = 26in
L + w = 13in
L + 4 = 13in
L = 9in
Dimensions of the Original rectangle were 4in by 9in