| ( | 1239 20 | ( | 1 | + | 20 100 | ) | ) | + | ( | 5 100 | x | ) | = | x |
| 方程左边 = | 1239 20 | ( | 1 | + | 20 100 | ) | + | ( | 5 100 | x | ) |
| = | 1239 20 | × | 1 | + | 1239 20 | × | 20 100 | + | ( | 5 100 | x | ) |
| = | 1239 20 | + | 1239 100 | + | ( | 5 100 | x | ) |
| = | 3717 50 | + | ( | 5 100 | x | ) |
| = | 3717 50 | + | 5 100 | x |
3717 50 | + | 5 100 | x | = | x |
5 100 | x | − | x | = | - | 3717 50 |
| - | 19 20 | x | = | - | 3717 50 |
3717 50 | = | 19 20 | x |
19 20 | x | = | 3717 50 |
| x | = | 3717 50 | ÷ | 19 20 |
| = | 3717 50 | × | 20 19 |
| = | 3717 5 | × | 2 19 |
| x | = | 7434 95 |
| x | = | 78.252632 |