28 . (4*3 - 2*1) * 2 + 4*4*2 + 4*3 + 4*1* 3 + 4*2*2 = 20 + 32 + 12 + 16 = 80 см2
29. (4 * 4 - 2*2)* 2 + 4*1 * 4 + 2 * 1 * 4 = 24 + 16 + 8 = 48 см2
30. 2 * 1 * 5 + 2*2 * 2 + 3 * 2 = 10 + 8 + 6 = 24 см2
31. 2 * 1 * 4 + 2 * 2 * 4 + (3 * 3 - 2 * 1) * 2 = 8 + 16 + 14 = 38 см2