3 20 | ( | 200 | + | x | ) | = | 11 100 | ( | 300 | + | x | ) |
| 方程左边 = | 3 20 | × | 200 | + | 3 20 | x |
| = | 30 | + | 3 20 | x |
| 30 | + | 3 20 | x | = | 11 100 | ( | 300 | + | x | ) |
| 方程右边 = | 11 100 | × | 300 | + | 11 100 | x |
| = | 33 | + | 11 100 | x |
| 30 | + | 3 20 | x | = | 33 | + | 11 100 | x |
3 20 | x | − | 11 100 | x | = | 33 | − | 30 |
1 25 | x | = | 33 | − | 30 |
1 25 | x | = | 3 |
| x | = | 3 | ÷ | 1 25 |
| = | 3 | × | 25 |
| x | = | 75 |