| ( | 3 | − | y | ÷ | 3 | ) | ( | 6 | − | 5 | y | ÷ | 3 | ) | = | 0 |
| 方程左边 = | 3 | ( | 6 | − | 5 | y | ÷ | 3 | ) | − | y | ÷ | 3 | × | ( | 6 | − | 5 | y | ÷ | 3 | ) |
| = | 3 | × | 6 | − | 3 | × | 5 | y | ÷ | 3 | − | y | × | 1 3 | ( | 6 | − | 5 | y | ÷ | 3 | ) |
| = | 18 | − | 5 | y | − | y | × | 1 3 | ( | 6 | − | 5 | y | ÷ | 3 | ) |
| = | 18 | − | 5 | y | − | y | × | 1 3 | × | 6 | + | y | × | 1 3 | × | 5 | y | ÷ | 3 |
| = | 18 | − | 5 | y | − | y | × | 2 | + | y | × | 5 9 | y |
| = | 18 | − | 7 | y | + | y | × | 5 9 | y |
| 18 | − | 7 | y | + | y | × | 5 9 | y | = | 0 |
| y1= | 18 5 |
| y2=9 |