A, 25 + 0 < 45 - 12 B, 12 + 23 < 89 - 34C, 19 - 4 < 25 D, 30...

Bài 4:a, 25 + 0 < 45 - 12 b, 12 + 23 < 89 - 34c, 19 - 4 < 25 d, 30 + 40 = 60 + 10e, 40 + 15 < 58 f, 42 + 5 < 58 - 8g, 75 > 23 + 34 h, 20 + 35 < 56