| ( | 9 10 | + | x | ) | ÷ | ( | x | + | 1 | ) | = | 199 200 |
| 方程两边同时乘以: | ( | x | + | 1 | ) |
| ( | 9 10 | + | x | ) | = | 199 200 | ( | x | + | 1 | ) |
9 10 | + | x | = | 199 200 | ( | x | + | 1 | ) |
9 10 | + | x | = | 199 200 | x | + | 199 200 | × | 1 |
9 10 | + | x | = | 199 200 | x | + | 199 200 |
| x | − | 199 200 | x | = | 199 200 | − | 9 10 |
1 200 | x | = | 199 200 | − | 9 10 |
1 200 | x | = | 19 200 |
| x | = | 19 200 | ÷ | 1 200 |
| = | 19 200 | × | 200 |
| = | 19 | × | 1 |
| x | = | 19 |