| 99 | ÷ | 8 | − | 9 | ( | 6 | − | M | ) | ÷ | 2 | = | 99 | ÷ | 16 |
| 方程左边 = | 99 8 | − | 9 2 | ( | 6 | − | M | ) |
99 8 | − | 9 2 | ( | 6 | − | M | ) | = | 99 | ÷ | 16 |
| 方程左边 = | 99 8 | − | 9 2 | × | 6 | + | 9 2 | M |
| = | 99 8 | − | 27 | + | 9 2 | M |
| = | - | 117 8 | + | 9 2 | M |
| - | 117 8 | + | 9 2 | M | = | 99 | ÷ | 16 |
| 方程右边 = | 99 16 |
| - | 117 8 | + | 9 2 | M | = | 99 16 |
9 2 | M | = | 99 16 | + | 117 8 |
9 2 | M | = | 333 16 |
| M | = | 333 16 | ÷ | 9 2 |
| = | 333 16 | × | 2 9 |
| = | 37 8 | × | 1 |
| M | = | 37 8 |
| M | = | 4.625 |