| 21 | ( | 31 | x | + | 30 | ) | − | 53119 | = | 26 | x | + | 11 |
| Left side of the equation = | 21 | × | 31 | x | + | 21 | × | 30 | − | 53119 |
| = | 651 | x | + | 630 | − | 53119 |
| = | 651 | x | − | 52489 |
| 651 | x | − | 52489 | = | 26 | x | + | 11 |
| 651 | x | − | 26 | x | = | 11 | + | 52489 |
| 625 | x | = | 11 | + | 52489 |
| 625 | x | = | 52500 |
| x | = | 52500 | ÷ | 625 |
| = | 52500 | × | 1 625 |
| = | 84 | × | 1 |
| x | = | 84 |