P = 2(L + W)
P = 40
L = W + 6
40 = 2(W + 6 + W)
40 = 2(2W + 6)
40 = 4W + 12
40 - 12 = 4W
28 = 4W
28/4 = W
7 = W....so the width is 7 cm
L = W + 6
L = 7 + 6
L = 13....and the length is 13 cm
the area is the length times the width
A = L * W
A = 13 * 7
A = 91 cm^2 <===