The length of a rectangle is twice its width. the perimeter of the rectangle is 36 cm. calculate the area of the rectangle

Length = 2(width)
perimeter = 36 cm

using variables where x = width and y = length

Perimeter = 2x + 2y = 36 cm
y = 2x

solving for length 2x + 2(2x) = 36 cm
                             2x + 4x = 36 cm
                             6x = 36 cm
                               x = 6 cm
                              
                          so y = 2(6 cm) = 12 cm

area of rectangle = 12 cm * 6 cm = 72 cm^2