| ( | 2 | × | 5 | − | 1 | ) | × | 64 | = | ( | 5 | + | a | ) | × | 1600 |
| 方程左边 = | 2 | × | 5 | × | 64 | − | 1 | × | 64 |
| = | 640 | − | 64 |
| = | 576 |
| 576 | = | ( | 5 | + | a | ) | × | 1600 |
| 方程右边 = | 5 | × | 1600 | + | a | × | 1600 |
| = | 8000 | + | a | × | 1600 |
| 576 | = | 8000 | + | 1600 | a |
| - | 1600 | a | = | 8000 | − | 576 |
| - | 1600 | a | = | 7424 |
| - | 7424 | = | 1600 | a |
| 1600 | a | = | - | 7424 |
| a | = | - | 7424 | ÷ | 1600 |
| = | - | 7424 | × | 1 1600 |
| = | - | 116 | × | 1 25 |
| a | = | - | 116 25 |
| a | = | - 4.64 |