| ( | ( | Y | − | 4000 | ) | − | 19 20 | ( | Y | − | 4000 | ) | ÷ | 4 | × | 3 | ) | × | 25 100 | = | 0 |
| 方程左边 = | ( | Y | − | 4000 | ) | × | 25 100 | − | 19 20 | ( | Y | − | 4000 | ) | ÷ | 4 | × | 3 | × | 25 100 |
| = | ( | Y | − | 4000 | ) | × | 25 100 | − | 57 320 | ( | Y | − | 4000 | ) |
| = | Y | × | 25 100 | − | 4000 | × | 25 100 | − | 57 320 | ( | Y | − | 4000 | ) |
| = | Y | × | 25 100 | − | 1000 | − | 57 320 | ( | Y | − | 4000 | ) |
| = | 25 100 | Y | − | 1000 | − | 57 320 | Y | + | 57 320 | × | 4000 |
| = | 25 100 | Y | − | 1000 | − | 57 320 | Y | + | 1425 2 |
| = | 23 320 | Y | − | 575 2 |
23 320 | Y | − | 575 2 | = | 0 |
23 320 | Y | = | 0 | + | 575 2 |
23 320 | Y | = | 575 2 |
| Y | = | 575 2 | ÷ | 23 320 |
| = | 575 2 | × | 320 23 |
| = | 25 | × | 160 |
| Y | = | 4000 |