| ( | 102 | + | x | ) | ÷ | ( | 103 | + | x | ) | = | 999 1000 |
| 方程两边同时乘以: | ( | 103 | + | x | ) |
| ( | 102 | + | x | ) | = | 999 1000 | ( | 103 | + | x | ) |
| 102 | + | x | = | 999 1000 | ( | 103 | + | x | ) |
| 102 | + | x | = | 999 1000 | × | 103 | + | 999 1000 | x |
| 102 | + | x | = | 102897 1000 | + | 999 1000 | x |
| x | − | 999 1000 | x | = | 102897 1000 | − | 102 |
1 1000 | x | = | 102897 1000 | − | 102 |
1 1000 | x | = | 897 1000 |
| x | = | 897 1000 | ÷ | 1 1000 |
| = | 897 1000 | × | 1000 |
| = | 897 | × | 1 |
| x | = | 897 |