| X | × | 117 100 | + | ( | 300 | − | X | ) | × | 59 50 | − | 300 | = | 42 |
| Left side of the equation = | 117 100 | X | + | 300 | × | 59 50 | − | X | × | 59 50 | − | 300 |
| = | 117 100 | X | + | 354 | − | X | × | 59 50 | − | 300 |
| = | - | 1 100 | X | + | 54 |
| - | 1 100 | X | + | 54 | = | 42 |
| - | 1 100 | X | = | 42 | − | 54 |
| - | 1 100 | X | = | - | 12 |
| 12 | = | 1 100 | X |
1 100 | X | = | 12 |
| X | = | 12 | ÷ | 1 100 |
| = | 12 | × | 100 |
| X | = | 1200 |