| 12 | x | + | ( | 4500 | − | x | ) | × | 15 | = | 61500 |
| Left side of the equation = | 12 | x | + | 4500 | × | 15 | − | x | × | 15 |
| = | 12 | x | + | 67500 | − | x | × | 15 |
| = | - | 3 | x | + | 67500 |
| - | 3 | x | + | 67500 | = | 61500 |
| - | 3 | x | = | 61500 | − | 67500 |
| - | 3 | x | = | - | 6000 |
| 6000 | = | 3 | x |
| 3 | x | = | 6000 |
| x | = | 6000 | ÷ | 3 |
| = | 6000 | × | 1 3 |
| = | 2000 | × | 1 |
| x | = | 2000 |