51+19+3×6-(47-42)-12 по действиям
51+19+3×6-(47-42)-12=70+18-5-12=71
1) 3 × 6 = 18
2) 47 - 42 = 5
3) 51 + 19 = 70
4) 70 + 18 = 88
5) 88 - 5 = 83
6) 83 - 12 = 71