| ( | 10 | − | 8 | ) | ( | 200 | − | X | ) | = | 0 |
| Left side of the equation = | 10 | ( | 200 | − | X | ) | − | 8 | ( | 200 | − | X | ) |
| = | 10 | × | 200 | − | 10 | X | − | 8 | ( | 200 | − | X | ) |
| = | 2000 | − | 10 | X | − | 8 | ( | 200 | − | X | ) |
| = | 2000 | − | 10 | X | − | 8 | × | 200 | + | 8 | X |
| = | 2000 | − | 10 | X | − | 1600 | + | 8 | X |
| = | 400 | − | 2 | X |
| 400 | − | 2 | X | = | 0 |
| - | 2 | X | = | 0 | − | 400 |
| - | 2 | X | = | - | 400 |
| 400 | = | 2 | X |
| 2 | X | = | 400 |
| X | = | 400 | ÷ | 2 |
| = | 400 | × | 1 2 |
| = | 200 | × | 1 |
| X | = | 200 |