| x | − | ( | ( | 20000 | + | x | ) | × | 1 50 | + | 1 5 | x | ) | = | 900 | × | 12 |
| 方程左边 = | x | − | ( | 20000 | + | x | ) | × | 1 50 | − | 1 5 | x |
| = | 4 5 | x | − | ( | 20000 | + | x | ) | × | 1 50 |
| = | 4 5 | x | − | 20000 | × | 1 50 | − | x | × | 1 50 |
| = | 4 5 | x | − | 400 | − | x | × | 1 50 |
| = | 39 50 | x | − | 400 |
39 50 | x | − | 400 | = | 900 | × | 12 |
| 方程右边 = | 10800 |
39 50 | x | − | 400 | = | 10800 |
39 50 | x | = | 10800 | + | 400 |
39 50 | x | = | 11200 |
| x | = | 11200 | ÷ | 39 50 |
| = | 11200 | × | 50 39 |
| x | = | 560000 39 |
| x | = | 14358.974359 |