| - | 450 | + | x | ( | 1 | + | 2 100 | ) | × | 690 | = | 500 |
| Left side of the equation = | - | 450 | + | x | × | 1 | × | 690 | + | x | × | 2 100 | × | 690 |
| = | - | 450 | + | x | × | 690 | + | x | × | 69 5 |
| = | - | 450 | + | 3519 5 | x |
| - | 450 | + | 3519 5 | x | = | 500 |
3519 5 | x | = | 500 | + | 450 |
3519 5 | x | = | 950 |
| x | = | 950 | ÷ | 3519 5 |
| = | 950 | × | 5 3519 |
| x | = | 4750 3519 |
| x | = | 1.349815 |