| 0 | = | 7 20 | Q | − | ( | 120 | + | 1 5 | Q | ) | − | 927 4 |
| Right side of the equation = | 7 20 | Q | − | 120 | − | 1 5 | Q | − | 927 4 |
| = | 3 20 | Q | − | 1407 4 |
| 0 | = | 3 20 | Q | − | 1407 4 |
| - | 3 20 | Q | = | - | 1407 4 | − | 0 |
| - | 3 20 | Q | = | - | 1407 4 |
1407 4 | = | 3 20 | Q |
3 20 | Q | = | 1407 4 |
| Q | = | 1407 4 | ÷ | 3 20 |
| = | 1407 4 | × | 20 3 |
| = | 469 | × | 5 |
| Q | = | 2345 |