| 58000 | = | ( | 50 | − | x | ) | × | 3600 | − | 50000 |
| Right side of the equation = | 50 | × | 3600 | − | x | × | 3600 | − | 50000 |
| = | 180000 | − | x | × | 3600 | − | 50000 |
| = | 130000 | − | 3600 | x |
| 58000 | = | 130000 | − | 3600 | x |
| 3600 | x | = | 130000 | − | 58000 |
| 3600 | x | = | 72000 |
| x | = | 72000 | ÷ | 3600 |
| = | 72000 | × | 1 3600 |
| = | 20 | × | 1 |
| x | = | 20 |