算24点：11,-7,9,-12

1: (7 + 11) ÷ 9 × 12
2: ((7 + 11) ÷ 9) × 12
3: (7 + 11) ÷ (9 ÷ 12)
4: (7 + 11) × 12 ÷ 9
5: ((7 + 11) × 12) ÷ 9
6: (7 + 11) × (12 ÷ 9)
7: (11 + 7) ÷ 9 × 12
8: ((11 + 7) ÷ 9) × 12
9: (11 + 7) ÷ (9 ÷ 12)
10: (11 - 7) × 9 - 12
11: ((11 - 7) × 9) - 12
12: (11 + 7) × 12 ÷ 9
13: ((11 + 7) × 12) ÷ 9
14: (11 + 7) × (12 ÷ 9)
15: (9 × (11 - 7)) - 12
16: 9 × (11 - 7) - 12
17: (12 × (7 + 11)) ÷ 9
18: 12 × (7 + 11) ÷ 9
19: 12 × ((7 + 11) ÷ 9)
20: (12 × (11 + 7)) ÷ 9
21: 12 × (11 + 7) ÷ 9
22: 12 × ((11 + 7) ÷ 9)
23: 12 ÷ 9 ×(7 + 11)
24: (12 ÷ 9) × (7 + 11)
25: 12 ÷ (9 ÷ (7 + 11))
26: 12 ÷ 9 ×(11 + 7)
27: (12 ÷ 9) × (11 + 7)
28: 12 ÷ (9 ÷ (11 + 7))

(-7-11 ) ÷ 9 × (-12)

(-7-11)/9*(-12)