| x | + | 8 5 | ( | 1 | − | x | ) | = | 21 100 |
| Left side of the equation = | x | + | 8 5 | × | 1 | − | 8 5 | x |
| = | x | + | 8 5 | − | 8 5 | x |
| = | - | 3 5 | x | + | 8 5 |
| - | 3 5 | x | + | 8 5 | = | 21 100 |
| - | 3 5 | x | = | 21 100 | − | 8 5 |
| - | 3 5 | x | = | - | 139 100 |
139 100 | = | 3 5 | x |
3 5 | x | = | 139 100 |
| x | = | 139 100 | ÷ | 3 5 |
| = | 139 100 | × | 5 3 |
| = | 139 20 | × | 1 3 |
| x | = | 139 60 |
| x | = | 2.316667 |