| 25 | x | + | 45 | ( | 1200 | − | x | ) | = | 40000 |
| Left side of the equation = | 25 | x | + | 45 | × | 1200 | − | 45 | x |
| = | 25 | x | + | 54000 | − | 45 | x |
| = | - | 20 | x | + | 54000 |
| - | 20 | x | + | 54000 | = | 40000 |
| - | 20 | x | = | 40000 | − | 54000 |
| - | 20 | x | = | - | 14000 |
| 14000 | = | 20 | x |
| 20 | x | = | 14000 |
| x | = | 14000 | ÷ | 20 |
| = | 14000 | × | 1 20 |
| = | 700 | × | 1 |
| x | = | 700 |