23 5 | ( | 50 | + | a | ) | = | ( | 10 | − | 23 5 | ) | ( | 50 | − | a | ) |
| 方程左边 = | 23 5 | × | 50 | + | 23 5 | a |
| = | 230 | + | 23 5 | a |
| 230 | + | 23 5 | a | = | ( | 10 | − | 23 5 | ) | ( | 50 | − | a | ) |
| 方程右边 = | 10 | ( | 50 | − | a | ) | − | 23 5 | ( | 50 | − | a | ) |
| = | 10 | × | 50 | − | 10 | a | − | 23 5 | ( | 50 | − | a | ) |
| = | 500 | − | 10 | a | − | 23 5 | ( | 50 | − | a | ) |
| = | 500 | − | 10 | a | − | 23 5 | × | 50 | + | 23 5 | a |
| = | 500 | − | 10 | a | − | 230 | + | 23 5 | a |
| = | 270 | − | 27 5 | a |
| 230 | + | 23 5 | a | = | 270 | − | 27 5 | a |
23 5 | a | + | 27 5 | a | = | 270 | − | 230 |
| 10 | a | = | 270 | − | 230 |
| 10 | a | = | 40 |
| a | = | 40 | ÷ | 10 |
| = | 40 | × | 1 10 |
| = | 4 | × | 1 |
| a | = | 4 |