| ( | 85 | ( | 1 | + | 20 100 | ) | ) | + | ( | 5 100 | x | ) | = | x |
| 方程左边 = | 85 | ( | 1 | + | 20 100 | ) | + | ( | 5 100 | x | ) |
| = | 85 | × | 1 | + | 85 | × | 20 100 | + | ( | 5 100 | x | ) |
| = | 85 | + | 17 | + | ( | 5 100 | x | ) |
| = | 102 | + | ( | 5 100 | x | ) |
| = | 102 | + | 5 100 | x |
| 102 | + | 5 100 | x | = | x |
5 100 | x | − | x | = | - | 102 |
| - | 19 20 | x | = | - | 102 |
| 102 | = | 19 20 | x |
19 20 | x | = | 102 |
| x | = | 102 | ÷ | 19 20 |
| = | 102 | × | 20 19 |
| x | = | 2040 19 |
| x | = | 107.368421 |