6 100 | b | + | 20 100 | ( | 1 | − | b | ) | = | 13 100 |
| 方程左边 = | 6 100 | b | + | 20 100 | × | 1 | − | 20 100 | b |
| = | 6 100 | b | + | 1 5 | − | 20 100 | b |
| = | - | 7 50 | b | + | 1 5 |
| - | 7 50 | b | + | 1 5 | = | 13 100 |
| - | 7 50 | b | = | 13 100 | − | 1 5 |
| - | 7 50 | b | = | - | 7 100 |
7 100 | = | 7 50 | b |
7 50 | b | = | 7 100 |
| b | = | 7 100 | ÷ | 7 50 |
| = | 7 100 | × | 50 7 |
| = | 1 2 | × | 1 |
| b | = | 1 2 |
| b | = | 0.5 |