| ( | x | − | 40 | ) | ( | - | 10 | + | 740 | ) | = | 2400 |
| 方程左边 = | x | ( | - | 10 | + | 740 | ) | − | 40 | ( | - | 10 | + | 740 | ) |
| = | - | x | × | 10 | + | x | × | 740 | − | 40 | ( | - | 10 | + | 740 | ) |
| = | 730 | x | − | 40 | ( | - | 10 | + | 740 | ) |
| = | 730 | x | + | 40 | × | 10 | − | 40 | × | 740 |
| = | 730 | x | + | 400 | − | 29600 |
| = | 730 | x | − | 29200 |
| 730 | x | − | 29200 | = | 2400 |
| 730 | x | = | 2400 | + | 29200 |
| 730 | x | = | 31600 |
| x | = | 31600 | ÷ | 730 |
| = | 31600 | × | 1 730 |
| = | 3160 | × | 1 73 |
| x | = | 3160 73 |
| x | = | 43.287671 |