| ( | x | − | 10 | ) | ÷ | 300 | = | ( | 15 | − | x | ) | ÷ | 240 |
| 方程左边 = | x | × | 1 300 | − | 10 | × | 1 300 |
| = | x | × | 1 300 | − | 1 30 |
1 300 | x | − | 1 30 | = | ( | 15 | − | x | ) | ÷ | 240 |
| 方程右边 = | 15 | × | 1 240 | − | x | × | 1 240 |
| = | 1 16 | − | x | × | 1 240 |
1 300 | x | − | 1 30 | = | 1 16 | − | 1 240 | x |
1 300 | x | + | 1 240 | x | = | 1 16 | + | 1 30 |
3 400 | x | = | 1 16 | + | 1 30 |
3 400 | x | = | 23 240 |
| x | = | 23 240 | ÷ | 3 400 |
| = | 23 240 | × | 400 3 |
| = | 23 3 | × | 5 3 |
| x | = | 115 9 |
| x | = | 12.777778 |