1. P = 4 x L
L = 2,1 dm = 2100 cm
P = 4 x 2100 cm = 8400 cm
2. P = L1 + L2 + L3
L1 = 0,3 m = 30 cm
L2 = 2 dm = 20 cm
L3 = 210 mm = 21 cm
P= 30 + 20 + 21 = 71 cm
3. P = 2L + 2l
l = 500 mm = 50 cm
L = 0,7 m = 70 cm
P = 2x50 + 2x70
P = 100 + 140 = 240
4. P = 2L + 2l
L = 2l = 2x2,3 = 4,6 m = 460 cm
l = 2,3 m = 230 cm
P = 2x230 + 2x460 = 460 + 920 = 1380 cm