| ( | 14 | − | x | ) | ( | 100 | + | 5 | x | ) | + | 1400 | = | 2020 |
| 方程左边 = | 14 | ( | 100 | + | 5 | x | ) | − | x | ( | 100 | + | 5 | x | ) | + | 1400 |
| = | 14 | × | 100 | + | 14 | × | 5 | x | − | x | ( | 100 | + | 5 | x | ) | + | 1400 |
| = | 1400 | + | 70 | x | − | x | ( | 100 | + | 5 | x | ) | + | 1400 |
| = | 2800 | + | 70 | x | − | x | ( | 100 | + | 5 | x | ) |
| = | 2800 | + | 70 | x | − | x | × | 100 | − | x | × | 5 | x |
| = | 2800 | − | 30 | x | − | x | × | 5 | x |
| 2800 | − | 30 | x | − | x | × | 5 | x | = | 2020 |