Calculer :

1. \( = [8 + (12 \div 4)] \times 2 \)
2. \( = 18 \div [3 \times (4 - 2)] \)
3. \( = 7 + (5 \times 2) - (12 \div 3) \)
4. \( = (30 \div 5) + 6 \times (8 - 6) \)