| 15000 | − | 10 | X | + | 200 | ( | 70 | − | X | ) | + | 80 | ( | 10 | + | X | ) | = | 25900 |
| Left side of the equation = | 15000 | − | 10 | X | + | 200 | × | 70 | − | 200 | X | + | 80 | ( | 10 | + | X | ) |
| = | 15000 | − | 10 | X | + | 14000 | − | 200 | X | + | 80 | ( | 10 | + | X | ) |
| = | 29000 | − | 210 | X | + | 80 | ( | 10 | + | X | ) |
| = | 29000 | − | 210 | X | + | 80 | × | 10 | + | 80 | X |
| = | 29000 | − | 210 | X | + | 800 | + | 80 | X |
| = | 29800 | − | 130 | X |
| 29800 | − | 130 | X | = | 25900 |
| - | 130 | X | = | 25900 | − | 29800 |
| - | 130 | X | = | - | 3900 |
| 3900 | = | 130 | X |
| 130 | X | = | 3900 |
| X | = | 3900 | ÷ | 130 |
| = | 3900 | × | 1 130 |
| = | 30 | × | 1 |
| X | = | 30 |