| ( | 69 | ( | 1 | + | 15 100 | ) | ) | + | ( | 8 100 | x | ) | = | x |
| 方程左边 = | 69 | ( | 1 | + | 15 100 | ) | + | ( | 8 100 | x | ) |
| = | 69 | × | 1 | + | 69 | × | 15 100 | + | ( | 8 100 | x | ) |
| = | 69 | + | 207 20 | + | ( | 8 100 | x | ) |
| = | 1587 20 | + | ( | 8 100 | x | ) |
| = | 1587 20 | + | 8 100 | x |
1587 20 | + | 8 100 | x | = | x |
8 100 | x | − | x | = | - | 1587 20 |
| - | 23 25 | x | = | - | 1587 20 |
1587 20 | = | 23 25 | x |
23 25 | x | = | 1587 20 |
| x | = | 1587 20 | ÷ | 23 25 |
| = | 1587 20 | × | 25 23 |
| = | 69 4 | × | 5 |
| x | = | 345 4 |
| x | = | 86.25 |