87 2000 | x | + | 19 400 | ( | 68 | − | x | ) | = | 1531 500 |
| 方程左边 = | 87 2000 | x | + | 19 400 | × | 68 | − | 19 400 | x |
| = | 87 2000 | x | + | 323 100 | − | 19 400 | x |
| = | - | 1 250 | x | + | 323 100 |
| - | 1 250 | x | + | 323 100 | = | 1531 500 |
| - | 1 250 | x | = | 1531 500 | − | 323 100 |
| - | 1 250 | x | = | - | 21 125 |
21 125 | = | 1 250 | x |
1 250 | x | = | 21 125 |
| x | = | 21 125 | ÷ | 1 250 |
| = | 21 125 | × | 250 |
| = | 21 | × | 2 |
| x | = | 42 |