| ( | 27 1000 | − | x | ) | ( | 7 200 | − | x | ) | = | x | ÷ | 150000000 |
| 方程左边 = | 27 1000 | ( | 7 200 | − | x | ) | − | x | ( | 7 200 | − | x | ) |
| = | 27 1000 | × | 7 200 | − | 27 1000 | x | − | x | ( | 7 200 | − | x | ) |
| = | 189 200000 | − | 27 1000 | x | − | x | ( | 7 200 | − | x | ) |
| = | 189 200000 | − | 27 1000 | x | − | x | × | 7 200 | + | x | x |
| = | 189 200000 | − | 31 500 | x | + | x | x |
189 200000 | − | 31 500 | x | + | x | x | = | x | ÷ | 150000000 |