| 2 | × | 5 | = | ( | 2 | + | 3 | ) | ( | 15 | − | x | ) |
| 方程左边 = | 10 |
| 10 | = | ( | 2 | + | 3 | ) | ( | 15 | − | x | ) |
| 方程右边 = | 2 | ( | 15 | − | x | ) | + | 3 | ( | 15 | − | x | ) |
| = | 2 | × | 15 | − | 2 | x | + | 3 | ( | 15 | − | x | ) |
| = | 30 | − | 2 | x | + | 3 | ( | 15 | − | x | ) |
| = | 30 | − | 2 | x | + | 3 | × | 15 | − | 3 | x |
| = | 30 | − | 2 | x | + | 45 | − | 3 | x |
| = | 75 | − | 5 | x |
| 10 | = | 75 | − | 5 | x |
| 5 | x | = | 75 | − | 10 |
| 5 | x | = | 65 |
| x | = | 65 | ÷ | 5 |
| = | 65 | × | 1 5 |
| = | 13 | × | 1 |
| x | = | 13 |