| ( | 2000 | − | X | ) | × | 21 100 | + | 79 100 | ( | - | 600 | − | X | ) | + | ( | 2000 | − | X | ) | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) | = | 0 |
| Left side of the equation = | 2000 | × | 21 100 | − | X | × | 21 100 | + | 79 100 | ( | - | 600 | − | X | ) | + | ( | 2000 | − | X | ) | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) |
| = | 420 | − | X | × | 21 100 | + | 79 100 | ( | - | 600 | − | X | ) | + | ( | 2000 | − | X | ) | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) |
| = | 420 | − | 21 100 | X | − | 79 100 | × | 600 | − | 79 100 | X | + | ( | 2000 | − | X | ) | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) |
| = | 420 | − | 21 100 | X | − | 474 | − | 79 100 | X | + | ( | 2000 | − | X | ) | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) |
| = | - | 54 | − | 1 | X | + | ( | 2000 | − | X | ) | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) |
| = | - | 54 | − | 1 | X | + | 2000 | × | 19 20 | − | X | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) |
| = | - | 54 | − | 1 | X | + | 1900 | − | X | × | 19 20 | + | 1 20 | ( | - | 640 | − | X | ) |
| = | 1846 | − | 39 20 | X | + | 1 20 | ( | - | 640 | − | X | ) |
| = | 1846 | − | 39 20 | X | − | 1 20 | × | 640 | − | 1 20 | X |
| = | 1846 | − | 39 20 | X | − | 32 | − | 1 20 | X |
| = | 1814 | − | 2 | X |
| 1814 | − | 2 | X | = | 0 |
| - | 2 | X | = | 0 | − | 1814 |
| - | 2 | X | = | - | 1814 |
| 1814 | = | 2 | X |
| 2 | X | = | 1814 |
| X | = | 1814 | ÷ | 2 |
| = | 1814 | × | 1 2 |
| = | 907 | × | 1 |
| X | = | 907 |