7. 67-(27+3) 67-27+3 80-25-15 80-(25-15) 70:10 70:7

Решение:
1) 67 - (27 + 3) = 67 - 30 = 37
2) 67 - 27 + 3 = 40 + 3 = 43
3) 80 - 25 - 15 = 55 - 15 = 40
4) 80 - (25 - 15) = 80 - 10 = 70
5) 70 : 10 = 7
6) 70 : 7 = 10