Răspuns :
l = 3,15 dam = > P = 3,15 x 4 = 12,6 dam
l = 18 cm = > P = 18 x 4 = 72 cm
l = 11mm = > P = 11 x 4 = 44 mm
l = 18 cm = > P = 18 x 4 = 72 cm
l = 11mm = > P = 11 x 4 = 44 mm