| 28 | ( | 70 | ÷ | ( | 70 | − | x | ) | ) | ( | 26 5 | − | 1 10 | x | ) | = | 140 |
| 28 | × | 70 | ÷ | ( | 70 | − | x | ) | × | ( | 26 5 | − | 1 10 | x | ) | = | 140 |
| 1960 | ÷ | ( | 70 | − | x | ) | × | ( | 26 5 | − | 1 10 | x | ) | = | 140 |
| 方程两边同时乘以: | ( | 70 | − | x | ) |
| 1960 | ( | 26 5 | − | 1 10 | x | ) | = | 140 | ( | 70 | − | x | ) |
| 1960 | × | 26 5 | − | 1960 | × | 1 10 | x | = | 140 | ( | 70 | − | x | ) |
| 1960 | × | 26 5 | − | 1960 | × | 1 10 | x | = | 140 | × | 70 | − | 140 | x |
| 10192 | − | 196 | x | = | 9800 | − | 140 | x |
| - | 196 | x | + | 140 | x | = | 9800 | − | 10192 |
| - | 56 | x | = | 9800 | − | 10192 |
| - | 56 | x | = | - | 392 |
| 392 | = | 56 | x |
| 56 | x | = | 392 |
| x | = | 392 | ÷ | 56 |
| = | 392 | × | 1 56 |
| = | 7 | × | 1 |
| x | = | 7 |