计算方法很多：
1:(5 + 7) ÷ 5 × 10
2:((5 + 7) ÷ 5) × 10
3:(5 + 7) ÷ (5 ÷ 10)
4:(5 + 7) × 10 ÷ 5
5:((5 + 7) × 10) ÷ 5
6:(5 + 7) × (10 ÷ 5)
7:10 ÷ 5 ×(5 + 7)
8:(10 ÷ 5) × (5 + 7)
9:10 ÷ (5 ÷ (5 + 7))
10:(10 × (5 + 7)) ÷ 5
11:10 × (5 + 7) ÷ 5
12:10 × ((5 + 7) ÷ 5)
13:10 ÷ 5 ×(7 + 5)
14:(10 ÷ 5) × (7 + 5)
15:10 ÷ (5 ÷ (7 + 5))
16:(10 × (7 + 5)) ÷ 5
17:10 × (7 + 5) ÷ 5
18:10 × ((7 + 5) ÷ 5)
19:(7 + 5) ÷ 5 × 10
20:((7 + 5) ÷ 5) × 10
21:(7 + 5) ÷ (5 ÷ 10)
22:(7 + 5) × 10 ÷ 5
23:((7 + 5) × 10) ÷ 5
24:(7 + 5) × (10 ÷ 5)