3 20 | x | + | 9 100 | ( | 1 | − | x | ) | = | 12 |
| Left side of the equation = | 3 20 | x | + | 9 100 | × | 1 | − | 9 100 | x |
| = | 3 20 | x | + | 9 100 | − | 9 100 | x |
| = | 3 50 | x | + | 9 100 |
3 50 | x | + | 9 100 | = | 12 |
3 50 | x | = | 12 | − | 9 100 |
3 50 | x | = | 1191 100 |
| x | = | 1191 100 | ÷ | 3 50 |
| = | 1191 100 | × | 50 3 |
| = | 397 2 | × | 1 |
| x | = | 397 2 |
| x | = | 198.5 |