Răspuns :
P = 64 cm
L = 3 l
P = 2 * L + 2 * l
64 = 2 * 3 l + 2 l
64 = 8 l
l = 64 : 8
l = 8 cm
L = 3 * 8
L = 24 cm
L = 3 l
P = 2 * L + 2 * l
64 = 2 * 3 l + 2 l
64 = 8 l
l = 64 : 8
l = 8 cm
L = 3 * 8
L = 24 cm