| ( | 40 | + | 2 5 | x | ) | ( | 1 | + | 1 100 | x | ) | = | 242 5 |
| 方程左边 = | 40 | ( | 1 | + | 1 100 | x | ) | + | 2 5 | x | ( | 1 | + | 1 100 | x | ) |
| = | 40 | × | 1 | + | 40 | × | 1 100 | x | + | 2 5 | x | ( | 1 | + | 1 100 | x | ) |
| = | 40 | + | 2 5 | x | + | 2 5 | x | ( | 1 | + | 1 100 | x | ) |
| = | 40 | + | 2 5 | x | + | 2 5 | x | × | 1 | + | 2 5 | x | × | 1 100 | x |
| = | 40 | + | 2 5 | x | + | 2 5 | x | + | 1 250 | x | x |
| = | 40 | + | 4 5 | x | + | 1 250 | x | x |
| 40 | + | 4 5 | x | + | 1 250 | x | x | = | 242 5 |