| 30 | ( | x | − | 280 | ) | = | 50 | ( | 334 | − | x | ) |
| 方程左边 = | 30 | x | − | 30 | × | 280 |
| = | 30 | x | − | 8400 |
| 30 | x | − | 8400 | = | 50 | ( | 334 | − | x | ) |
| 方程右边 = | 50 | × | 334 | − | 50 | x |
| = | 16700 | − | 50 | x |
| 30 | x | − | 8400 | = | 16700 | − | 50 | x |
| 30 | x | + | 50 | x | = | 16700 | + | 8400 |
| 80 | x | = | 16700 | + | 8400 |
| 80 | x | = | 25100 |
| x | = | 25100 | ÷ | 80 |
| = | 25100 | × | 1 80 |
| = | 1255 | × | 1 4 |
| x | = | 1255 4 |
| x | = | 313.75 |