| ( | ( | 100000 | ÷ | 2500 | ) | + | x | ) | × | 2500 | × | 4 5 | = | 100000 |
| 方程左边 = | ( | ( | 100000 | ÷ | 2500 | ) | + | x | ) | × | 2000 |
| ( | ( | 100000 | ÷ | 2500 | ) | + | x | ) | × | 2000 | = | 100000 |
| 方程左边 = | ( | 100000 | ÷ | 2500 | ) | × | 2000 | + | x | × | 2000 |
| = | 100000 | ÷ | 2500 | × | 2000 | + | 2000 | x |
| = | 80000 | + | 2000 | x |
| 80000 | + | 2000 | x | = | 100000 |
| 2000 | x | = | 100000 | − | 80000 |
| 2000 | x | = | 20000 |
| x | = | 20000 | ÷ | 2000 |
| = | 20000 | × | 1 2000 |
| = | 10 | × | 1 |
| x | = | 10 |