| 12000 | ( | X | − | 200 | ) | − | 720000 | − | 12000 | X | × | 5 100 | = | 12000 | × | 200 | × | 20 100 |
| Left side of the equation = | 12000 | ( | X | − | 200 | ) | − | 720000 | − | 600 | X |
| 12000 | ( | X | − | 200 | ) | − | 720000 | − | 600 | X | = | 12000 | × | 200 | × | 20 100 |
| Left side of the equation = | 12000 | X | − | 12000 | × | 200 | − | 720000 | − | 600 | X |
| = | 12000 | X | − | 2400000 | − | 720000 | − | 600 | X |
| = | 11400 | X | − | 3120000 |
| 11400 | X | − | 3120000 | = | 12000 | × | 200 | × | 20 100 |
| Right side of the equation = | 480000 |
| 11400 | X | − | 3120000 | = | 480000 |
| 11400 | X | = | 480000 | + | 3120000 |
| 11400 | X | = | 3600000 |
| X | = | 3600000 | ÷ | 11400 |
| = | 3600000 | × | 1 11400 |
| = | 6000 | × | 1 19 |
| X | = | 6000 19 |
| X | = | 315.789474 |