| ( | 110 | + | x | ) | × | 90 | = | ( | 90 | x | ) | × | 210 |
| 方程左边 = | 110 | × | 90 | + | x | × | 90 |
| = | 9900 | + | x | × | 90 |
| 9900 | + | 90 | x | = | ( | 90 | x | ) | × | 210 |
| 方程右边 = | 90 | x | × | 210 |
| = | 18900 | x |
| 9900 | + | 90 | x | = | 18900 | x |
| 90 | x | − | 18900 | x | = | - | 9900 |
| - | 18810 | x | = | - | 9900 |
| 9900 | = | 18810 | x |
| 18810 | x | = | 9900 |
| x | = | 9900 | ÷ | 18810 |
| = | 9900 | × | 1 18810 |
| = | 110 | × | 1 209 |
| x | = | 110 209 |
| x | = | 10 19 |
| x | = | 0.526316 |