| ( | Y | + | 300 | ) | ÷ | ( | Y | + | 585 | ) | = | 3 4 |
| 方程两边同时乘以: | ( | Y | + | 585 | ) |
| ( | Y | + | 300 | ) | = | 3 4 | ( | Y | + | 585 | ) |
| Y | + | 300 | = | 3 4 | ( | Y | + | 585 | ) |
| Y | + | 300 | = | 3 4 | Y | + | 3 4 | × | 585 |
| Y | + | 300 | = | 3 4 | Y | + | 1755 4 |
| Y | − | 3 4 | Y | = | 1755 4 | − | 300 |
1 4 | Y | = | 1755 4 | − | 300 |
1 4 | Y | = | 555 4 |
| Y | = | 555 4 | ÷ | 1 4 |
| = | 555 4 | × | 4 |
| = | 555 | × | 1 |
| Y | = | 555 |