| ( | 398 | + | x | ) | ÷ | ( | 441 | + | x | ) | = | 19 20 |
| 方程两边同时乘以: | ( | 441 | + | x | ) |
| ( | 398 | + | x | ) | = | 19 20 | ( | 441 | + | x | ) |
| 398 | + | x | = | 19 20 | ( | 441 | + | x | ) |
| 398 | + | x | = | 19 20 | × | 441 | + | 19 20 | x |
| 398 | + | x | = | 8379 20 | + | 19 20 | x |
| x | − | 19 20 | x | = | 8379 20 | − | 398 |
1 20 | x | = | 8379 20 | − | 398 |
1 20 | x | = | 419 20 |
| x | = | 419 20 | ÷ | 1 20 |
| = | 419 20 | × | 20 |
| = | 419 | × | 1 |
| x | = | 419 |