7 10 | ( | 3 | x | − | 5 | ) | + | 3 5 | ( | 2 | x | − | 5 | ) | = | 53 80 | ( | 5 | x | − | 10 | ) |
| 方程左边 = | 7 10 | × | 3 | x | − | 7 10 | × | 5 | + | 3 5 | ( | 2 | x | − | 5 | ) |
| = | 21 10 | x | − | 7 2 | + | 3 5 | ( | 2 | x | − | 5 | ) |
| = | 21 10 | x | − | 7 2 | + | 3 5 | × | 2 | x | − | 3 5 | × | 5 |
| = | 21 10 | x | − | 7 2 | + | 6 5 | x | − | 3 |
| = | 33 10 | x | − | 13 2 |
33 10 | x | − | 13 2 | = | 53 80 | ( | 5 | x | − | 10 | ) |
| 方程右边 = | 53 80 | × | 5 | x | − | 53 80 | × | 10 |
| = | 53 16 | x | − | 53 8 |
33 10 | x | − | 13 2 | = | 53 16 | x | − | 53 8 |
33 10 | x | − | 53 16 | x | = | - | 53 8 | + | 13 2 |
| - | 1 80 | x | = | - | 53 8 | + | 13 2 |
| - | 1 80 | x | = | - | 1 8 |
1 8 | = | 1 80 | x |
1 80 | x | = | 1 8 |
| x | = | 1 8 | ÷ | 1 80 |
| = | 1 8 | × | 80 |
| = | 1 | × | 10 |
| x | = | 10 |