12 5 | ( | 36 5 | x | + | 14 5 | ) | − | 2801 50 | = | 7 | x | + | 21 10 |
| 方程左边 = | 12 5 | × | 36 5 | x | + | 12 5 | × | 14 5 | − | 2801 50 |
| = | 432 25 | x | + | 168 25 | − | 2801 50 |
| = | 432 25 | x | − | 493 10 |
432 25 | x | − | 493 10 | = | 7 | x | + | 21 10 |
432 25 | x | − | 7 | x | = | 21 10 | + | 493 10 |
257 25 | x | = | 21 10 | + | 493 10 |
257 25 | x | = | 257 5 |
| x | = | 257 5 | ÷ | 257 25 |
| = | 257 5 | × | 25 257 |
| = | 257 | × | 5 257 |
| x | = | 1285 257 |
| x | = | 5 |