| 120 | x | + | ( | 1 | − | 40 100 | ) | ( | 500 | − | x | ) | − | 40000 | = | 20 100 | × | 40000 |
| Left side of the equation = | 120 | x | + | 1 | ( | 500 | − | x | ) | − | 40 100 | ( | 500 | − | x | ) | − | 40000 |
| = | 120 | x | + | 1 | × | 500 | − | 1 | x | − | 40 100 | ( | 500 | − | x | ) | − | 40000 |
| = | 120 | x | + | 500 | − | 1 | x | − | 40 100 | ( | 500 | − | x | ) | − | 40000 |
| = | 119 | x | − | 39500 | − | 40 100 | ( | 500 | − | x | ) |
| = | 119 | x | − | 39500 | − | 40 100 | × | 500 | + | 40 100 | x |
| = | 119 | x | − | 39500 | − | 200 | + | 40 100 | x |
| = | 597 5 | x | − | 39700 |
597 5 | x | − | 39700 | = | 20 100 | × | 40000 |
| Right side of the equation = | 8000 |
597 5 | x | − | 39700 | = | 8000 |
597 5 | x | = | 8000 | + | 39700 |
597 5 | x | = | 47700 |
| x | = | 47700 | ÷ | 597 5 |
| = | 47700 | × | 5 597 |
| = | 15900 | × | 5 199 |
| x | = | 79500 199 |
| x | = | 399.497487 |