| - | 450 | + | x | ( | 1 | − | 2 100 | ) | − | 690 | = | 500 |
| Left side of the equation = | - | 1140 | + | x | ( | 1 | − | 2 100 | ) |
| - | 1140 | + | x | ( | 1 | − | 2 100 | ) | = | 500 |
| Left side of the equation = | - | 1140 | + | x | × | 1 | − | x | × | 2 100 |
| = | - | 1140 | + | 49 50 | x |
| - | 1140 | + | 49 50 | x | = | 500 |
49 50 | x | = | 500 | + | 1140 |
49 50 | x | = | 1640 |
| x | = | 1640 | ÷ | 49 50 |
| = | 1640 | × | 50 49 |
| x | = | 82000 49 |
| x | = | 1673.469388 |