| ( | Y | × | 15 | ) | ÷ | ( | Y | × | 15 | ) | − | ( | 1500 | + | 2700 | ) | = | 5 4 |
| 方程两边同时乘以: | ( | Y | × | 15 | ) |
| ( | Y | × | 15 | ) | − | ( | 1500 | + | 2700 | ) | ( | Y | × | 15 | ) | = | 5 4 | ( | Y | × | 15 | ) |
| Y | × | 15 | − | ( | 1500 | + | 2700 | ) | ( | Y | × | 15 | ) | = | 5 4 | ( | Y | × | 15 | ) |
| Y | × | 15 | − | ( | 1500 | + | 2700 | ) | ( | Y | × | 15 | ) | = | 5 4 | Y | × | 15 |
| Y | × | 15 | − | ( | 1500 | + | 2700 | ) | ( | Y | × | 15 | ) | = | 75 4 | Y |
| 15 | Y | − | 1500 | ( | Y | × | 15 | ) | − | 2700 | ( | Y | × | 15 | ) | = | 75 4 | Y |
| 15 | Y | − | 1500 | Y | × | 15 | − | 2700 | ( | Y | × | 15 | ) | = | 75 4 | Y |
| 15 | Y | − | 22500 | Y | − | 2700 | ( | Y | × | 15 | ) | = | 75 4 | Y |
| - | 22485 | Y | − | 2700 | ( | Y | × | 15 | ) | = | 75 4 | Y |
| - | 22485 | Y | − | 2700 | Y | × | 15 | = | 75 4 | Y |
| - | 22485 | Y | − | 40500 | Y | = | 75 4 | Y |
| - | 62985 | Y | = | 75 4 | Y |
| - | 62985 | Y | − | 75 4 | Y | = | 0 |
| - | 252015 4 | Y | = | 0 |
| - | 0 | = | 252015 4 | Y |
252015 4 | Y | = | - | 0 |
| Y | = | - | 0 | ÷ | 252015 4 |
| = | - | 0 | × | 4 252015 |
| Y | = | 0 |
| Y | = | 0 |