| 3000 | = | ( | x | − | 800 | ) | × | 20 100 |
| Right side of the equation = | x | × | 20 100 | − | 800 | × | 20 100 |
| = | x | × | 20 100 | − | 160 |
| 3000 | = | 20 100 | x | − | 160 |
| - | 20 100 | x | = | - | 160 | − | 3000 |
| - | 20 100 | x | = | - | 3160 |
| 3160 | = | 20 100 | x |
20 100 | x | = | 3160 |
| x | = | 3160 | ÷ | 20 100 |
| = | 3160 | × | 100 20 |
| = | 158 | × | 100 |
| x | = | 15800 |