| X | − | ( | ( | X | − | 800 | ) | × | 20 100 | ) | = | 2000 |
| Left side of the equation = | X | − | ( | X | − | 800 | ) | × | 20 100 |
| = | X | − | X | × | 20 100 | + | 800 | × | 20 100 |
| = | X | − | X | × | 20 100 | + | 160 |
| = | 4 5 | X | + | 160 |
4 5 | X | + | 160 | = | 2000 |
4 5 | X | = | 2000 | − | 160 |
4 5 | X | = | 1840 |
| X | = | 1840 | ÷ | 4 5 |
| = | 1840 | × | 5 4 |
| = | 460 | × | 5 |
| X | = | 2300 |