| ( | 3 4 | x | − | 30 | ) | ÷ | 10 | = | ( | 3 4 | x | − | 18 | ) | ÷ | 14 |
| 方程左边 = | 3 4 | x | × | 1 10 | − | 30 | × | 1 10 |
| = | 3 40 | x | − | 3 |
3 40 | x | − | 3 | = | ( | 3 4 | x | − | 18 | ) | ÷ | 14 |
| 方程右边 = | 3 4 | x | × | 1 14 | − | 18 | × | 1 14 |
| = | 3 56 | x | − | 9 7 |
3 40 | x | − | 3 | = | 3 56 | x | − | 9 7 |
3 40 | x | − | 3 56 | x | = | - | 9 7 | + | 3 |
3 140 | x | = | - | 9 7 | + | 3 |
3 140 | x | = | 12 7 |
| x | = | 12 7 | ÷ | 3 140 |
| = | 12 7 | × | 140 3 |
| = | 4 | × | 20 |
| x | = | 80 |