| 20 | X | + | 35 | ( | 700 | − | X | ) | = | 20000 |
| Left side of the equation = | 20 | X | + | 35 | × | 700 | − | 35 | X |
| = | 20 | X | + | 24500 | − | 35 | X |
| = | - | 15 | X | + | 24500 |
| - | 15 | X | + | 24500 | = | 20000 |
| - | 15 | X | = | 20000 | − | 24500 |
| - | 15 | X | = | - | 4500 |
| 4500 | = | 15 | X |
| 15 | X | = | 4500 |
| X | = | 4500 | ÷ | 15 |
| = | 4500 | × | 1 15 |
| = | 300 | × | 1 |
| X | = | 300 |