| 40 | x | = | ( | 1 | ÷ | 3 | × | x | ) | ÷ | 40 | + | ( | 2 | ÷ | 3 | × | x | ) | ÷ | 40 |
| 方程右边 = | 1 | ÷ | 3 | × | x | × | 1 40 | + | ( | 2 | ÷ | 3 | × | x | ) | × | 1 40 |
| = | 1 120 | x | + | ( | 2 | ÷ | 3 | × | x | ) | × | 1 40 |
| = | 1 120 | x | + | 2 | ÷ | 3 | × | x | × | 1 40 |
| = | 1 120 | x | + | 1 60 | x |
| = | 1 40 | x |
| 40 | x | = | 1 40 | x |
| 40 | x | − | 1 40 | x | = | 0 |
1599 40 | x | = | 0 |
| x | = | 0 | ÷ | 1599 40 |
| = | 0 | × | 40 1599 |
| x | = | 0 |