| ( | ( | 3000 | − | x | ) | × | 3 10 | + | 300 | ) | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | = | x | − | 1 20 | × | 3000 |
| 方程左边 = | ( | 3000 | − | x | ) | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 3000 | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | − | x | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 900 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | − | x | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 900 | × | 1 | + | 900 | × | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | − | x | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 900 | + | 3 35 | ( | 3000 | − | x | ) | − | x | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 900 | + | 3 35 | × | 3000 | − | 3 35 | x | − | x | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 900 | + | 1800 7 | − | 3 35 | x | − | x | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 8100 7 | − | 3 35 | x | − | x | × | 3 10 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 8100 7 | − | 3 35 | x | − | x | × | 3 10 | × | 1 | − | x | × | 3 10 | × | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | + | 300 |
| = | 8100 7 | − | 3 35 | x | − | x | × | 3 10 | − | x | × | 1 35000 | ( | 3000 | − | x | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 8100 7 | − | 27 70 | x | − | x | × | 1 35000 | ( | 3000 | − | x | ) | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 8100 7 | − | 27 70 | x | − | x | × | 1 35000 | × | 3000 | + | x | × | 1 35000 | x | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 8100 7 | − | 27 70 | x | − | x | × | 3 35 | + | x | × | 1 35000 | x | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 8100 7 | − | 33 70 | x | + | x | × | 1 35000 | x | + | 300 | ( | 1 | + | 2 | ( | 3000 | − | x | ) | ÷ | 21000 | ) |
| = | 8100 7 | − | 33 70 | x | + | x | × | 1 35000 | x | + | 300 | × | 1 | + | 300 | × | 2 | ( | 3000 | − | x | ) | ÷ | 21000 |
| = | 8100 7 | − | 33 70 | x | + | x | × | 1 35000 | x | + | 300 | + | 1 35 | ( | 3000 | − | x | ) |
| = | 10200 7 | − | 33 70 | x | + | x | × | 1 35000 | x | + | 1 35 | ( | 3000 | − | x | ) |
| = | 10200 7 | − | 33 70 | x | + | x | × | 1 35000 | x | + | 1 35 | × | 3000 | − | 1 35 | x |
| = | 10200 7 | − | 33 70 | x | + | x | × | 1 35000 | x | + | 600 7 | − | 1 35 | x |
| = | 10800 7 | − | 1 2 | x | + | x | × | 1 35000 | x |
10800 7 | − | 1 2 | x | + | x | × | 1 35000 | x | = | x | − | 1 20 | × | 3000 |
| 方程右边 = | x | − | 150 |
10800 7 | − | 1 2 | x | + | x | × | 1 35000 | x | = | x | − | 150 |