| 6000 | × | 3 20 | ( | x | + | 7 10 | ) | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 30000 | × | 7 10 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| 方程左边 = | 900 | ( | x | + | 7 10 | ) | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 |
| 900 | ( | x | + | 7 10 | ) | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| 方程左边 = | 900 | x | + | 900 | × | 7 10 | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 |
| = | 900 | x | + | 630 | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 |
| = | 2500 | x | + | 21630 | + | 700 | ( | 3 10 | − | x | ) |
| = | 2500 | x | + | 21630 | + | 700 | × | 3 10 | − | 700 | x |
| = | 2500 | x | + | 21630 | + | 210 | − | 700 | x |
| = | 1800 | x | + | 21840 |
| 1800 | x | + | 21840 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| 方程右边 = | 16000 | × | 3 20 | x | + | 16000 | × | 3 20 | × | 7 10 | + | 16000 | × | 1 |
| = | 2400 | x | + | 1680 | + | 16000 |
| = | 2400 | x | + | 17680 |
| 1800 | x | + | 21840 | = | 2400 | x | + | 17680 |
| 1800 | x | − | 2400 | x | = | 17680 | − | 21840 |
| - | 600 | x | = | 17680 | − | 21840 |
| - | 600 | x | = | - | 4160 |
| 4160 | = | 600 | x |
| 600 | x | = | 4160 |
| x | = | 4160 | ÷ | 600 |
| = | 4160 | × | 1 600 |
| = | 104 | × | 1 15 |
| x | = | 104 15 |
| x | = | 6.933333 |