| 2400 | = | 80 | ( | 23 | − | x | ) | + | 80 | × | 19 20 | x | + | 17 20 | × | 80 | x |
| 方程右边 = | 80 | ( | 23 | − | x | ) | + | 76 | x | + | 68 | x |
| = | 80 | ( | 23 | − | x | ) | + | 144 | x |
| 2400 | = | 80 | ( | 23 | − | x | ) | + | 144 | x |
| 方程右边 = | 80 | × | 23 | − | 80 | x | + | 144 | x |
| = | 1840 | − | 80 | x | + | 144 | x |
| = | 1840 | + | 64 | x |
| 2400 | = | 1840 | + | 64 | x |
| - | 64 | x | = | 1840 | − | 2400 |
| - | 64 | x | = | - | 560 |
| 560 | = | 64 | x |
| 64 | x | = | 560 |
| x | = | 560 | ÷ | 64 |
| = | 560 | × | 1 64 |
| = | 35 | × | 1 4 |
| x | = | 35 4 |
| x | = | 8.75 |