| 350 | ( | x | + | 5 | ) | = | 300 | ( | x | + | 10 | ) |
| 方程左边 = | 350 | x | + | 350 | × | 5 |
| = | 350 | x | + | 1750 |
| 350 | x | + | 1750 | = | 300 | ( | x | + | 10 | ) |
| 方程右边 = | 300 | x | + | 300 | × | 10 |
| = | 300 | x | + | 3000 |
| 350 | x | + | 1750 | = | 300 | x | + | 3000 |
| 350 | x | − | 300 | x | = | 3000 | − | 1750 |
| 50 | x | = | 3000 | − | 1750 |
| 50 | x | = | 1250 |
| x | = | 1250 | ÷ | 50 |
| = | 1250 | × | 1 50 |
| = | 25 | × | 1 |
| x | = | 25 |