| - | 149 | ÷ | 16 | − | 11 | ÷ | 3 | × | r | = | - | 7 | ÷ | 4 | × | r | − | 5 | ÷ | 4 | × | ( | - | 4 | ÷ | 3 | × | r | + | 1 | ) |
| 方程左边 = | - | 149 16 | − | 11 3 | r |
| - | 149 16 | − | 11 3 | r | = | - | 7 | ÷ | 4 | × | r | − | 5 | ÷ | 4 | × | ( | - | 4 | ÷ | 3 | × | r | + | 1 | ) |
| 方程右边 = | - | 7 4 | r | − | 5 4 | ( | - | 4 | ÷ | 3 | × | r | + | 1 | ) |
| - | 149 16 | − | 11 3 | r | = | - | 7 4 | r | − | 5 4 | ( | - | 4 | ÷ | 3 | × | r | + | 1 | ) |
| 方程右边 = | - | 7 4 | r | + | 5 4 | × | 4 | ÷ | 3 | × | r | − | 5 4 | × | 1 |
| = | - | 7 4 | r | + | 5 3 | r | − | 5 4 |
| = | - | 1 12 | r | − | 5 4 |
| - | 149 16 | − | 11 3 | r | = | - | 1 12 | r | − | 5 4 |
| - | 11 3 | r | + | 1 12 | r | = | - | 5 4 | + | 149 16 |
| - | 43 12 | r | = | - | 5 4 | + | 149 16 |
| - | 43 12 | r | = | 129 16 |
| - | 129 16 | = | 43 12 | r |
43 12 | r | = | - | 129 16 |
| r | = | - | 129 16 | ÷ | 43 12 |
| = | - | 129 16 | × | 12 43 |
| = | - | 3 4 | × | 3 |
| r | = | - | 9 4 |
| r | = | - 2.25 |