| 4 | ÷ | 20 | + | ( | x | + | 4 | ) | ÷ | 12 | = | 1 |
| 方程左边 = | 1 5 | + | ( | x | + | 4 | ) | × | 1 12 |
1 5 | + | ( | x | + | 4 | ) | × | 1 12 | = | 1 |
| 方程左边 = | 1 5 | + | x | × | 1 12 | + | 4 | × | 1 12 |
| = | 1 5 | + | x | × | 1 12 | + | 1 3 |
| = | 8 15 | + | 1 12 | x |
8 15 | + | 1 12 | x | = | 1 |
1 12 | x | = | 1 | − | 8 15 |
1 12 | x | = | 7 15 |
| x | = | 7 15 | ÷ | 1 12 |
| = | 7 15 | × | 12 |
| = | 7 5 | × | 4 |
| x | = | 28 5 |
| x | = | 5.6 |