3.42 Восстановите цепочку вычислений

a)

1. 57 + 12 = 69
2. 69 : 3 = 23
3. 23 - 16 = 7
4. 7 - 14 = -7
5. -7 : 2 = -3.5
6. -3.5 + 8 = 4.5

б)

1. 25 × 4 = 100
2. 100 - 79 = 21
3. 21 × 3 = 63
4. 63 - 31 = 32
5. 32 : 4 = 8
6. 8 + 17 = 25