| ( | 2 5 | x | × | 70 | + | 3 5 | x | × | 30 | + | 16800 | ) | × | 9 10 | = | 10000 |
| 方程左边 = | 2 5 | x | × | 70 | × | 9 10 | + | 3 5 | x | × | 30 | × | 9 10 | + | 16800 | × | 9 10 |
| = | 126 5 | x | + | 81 5 | x | + | 15120 |
| = | 207 5 | x | + | 15120 |
207 5 | x | + | 15120 | = | 10000 |
207 5 | x | = | 10000 | − | 15120 |
207 5 | x | = | - | 5120 |
| x | = | - | 5120 | ÷ | 207 5 |
| = | - | 5120 | × | 5 207 |
| x | = | - | 25600 207 |
| x | = | - 123.671498 |