1) 28 * 3 - 57 = 84 - 57 = 27
2) 34 + 13.5 = 47.5
3) 98 – 23 * 4 + 24 = 98 - 92 + 24 = 6 + 24 = 30
4) 28 : 2 – 13 * 4 = 14 - 52 = -38
Ответ: 1) 27; 2) 47.5; 3) 30; 4) -38