| a | + | 300 | ÷ | 800 | = | 1900 | + | 2 | a | ÷ | 800 | + | a |
| 方程左边 = | a | + | 3 8 |
| a | + | 3 8 | = | 1900 | + | 2 | a | ÷ | 800 | + | a |
| 方程右边 = | 1900 | + | 1 400 | a | + | a |
| = | 1900 | + | 401 400 | a |
| a | + | 3 8 | = | 1900 | + | 401 400 | a |
| a | − | 401 400 | a | = | 1900 | − | 3 8 |
| - | 1 400 | a | = | 1900 | − | 3 8 |
| - | 1 400 | a | = | 15197 8 |
| - | 15197 8 | = | 1 400 | a |
1 400 | a | = | - | 15197 8 |
| a | = | - | 15197 8 | ÷ | 1 400 |
| = | - | 15197 8 | × | 400 |
| = | - | 15197 | × | 50 |
| a | = | - | 759850 |