| ( | 40 | − | x | ) | ( | 60 | + | 2 | x | ) | + | ( | 35 | − | x | ) | ( | 40 | + | 3 | x | ) | − | 3800 | = | 300 |
| 方程左边 = | 40 | ( | 60 | + | 2 | x | ) | − | x | ( | 60 | + | 2 | x | ) | + | ( | 35 | − | x | ) | ( | 40 | + | 3 | x | ) | − | 3800 |
| = | 40 | × | 60 | + | 40 | × | 2 | x | − | x | ( | 60 | + | 2 | x | ) | + | ( | 35 | − | x | ) | ( | 40 | + | 3 | x | ) | − | 3800 |
| = | 2400 | + | 80 | x | − | x | ( | 60 | + | 2 | x | ) | + | ( | 35 | − | x | ) | ( | 40 | + | 3 | x | ) | − | 3800 |
| = | - | 1400 | + | 80 | x | − | x | ( | 60 | + | 2 | x | ) | + | ( | 35 | − | x | ) | ( | 40 | + | 3 | x | ) |
| = | - | 1400 | + | 80 | x | − | x | × | 60 | − | x | × | 2 | x | + | ( | 35 | − | x | ) | ( | 40 | + | 3 | x | ) |
| = | - | 1400 | + | 20 | x | − | x | × | 2 | x | + | ( | 35 | − | x | ) | ( | 40 | + | 3 | x | ) |
| = | - | 1400 | + | 20 | x | − | x | × | 2 | x | + | 35 | ( | 40 | + | 3 | x | ) | − | x | ( | 40 | + | 3 | x | ) |
| = | - | 1400 | + | 20 | x | − | x | × | 2 | x | + | 35 | × | 40 | + | 35 | × | 3 | x | − | x |
| = | - | 1400 | + | 20 | x | − | x | × | 2 | x | + | 1400 | + | 105 | x | − | x | ( | 40 | + | 3 | x | ) |
| = | - | 0 | + | 125 | x | − | x | × | 2 | x | − | x | ( | 40 | + | 3 | x | ) |
| = | 125 | x | − | x | × | 2 | x | − | x | × | 40 | − | x | × | 3 | x |
| = | 85 | x | − | x | × | 2 | x | − | x | × | 3 | x |
| 85 | x | − | x | × | 2 | x | − | x | × | 3 | x | = | 300 |