| X | ÷ | 75 | + | ( | 7000 | − | X | ) | ÷ | 50 | = | 100 |
| Left side of the equation = | 1 75 | X | + | 7000 | × | 1 50 | − | X | × | 1 50 |
| = | 1 75 | X | + | 140 | − | X | × | 1 50 |
| = | - | 1 150 | X | + | 140 |
| - | 1 150 | X | + | 140 | = | 100 |
| - | 1 150 | X | = | 100 | − | 140 |
| - | 1 150 | X | = | - | 40 |
| 40 | = | 1 150 | X |
1 150 | X | = | 40 |
| X | = | 40 | ÷ | 1 150 |
| = | 40 | × | 150 |
| X | = | 6000 |