| 2000 | − | 1600 | × | 400 | + | 40 | x | = | 50 | x |
| Left side of the equation = | 2000 | − | 640000 | + | 40 | x |
| = | - | 638000 | + | 40 | x |
| - | 638000 | + | 40 | x | = | 50 | x |
| 40 | x | − | 50 | x | = | 638000 |
| - | 10 | x | = | 638000 |
| - | 638000 | = | 10 | x |
| 10 | x | = | - | 638000 |
| x | = | - | 638000 | ÷ | 10 |
| = | - | 638000 | × | 1 10 |
| = | - | 63800 | × | 1 |
| x | = | - | 63800 |