| 30 | × | 2 | ( | X | + | 2 | X | ) | + | 120 | X | × | 2 | X | + | 45 | = | 195 |
| 方程左边 = | 60 | ( | X | + | 2 | X | ) | + | 240 | X | X | + | 45 |
| 60 | ( | X | + | 2 | X | ) | + | 240 | X | X | + | 45 | = | 195 |
| 方程左边 = | 60 | X | + | 60 | × | 2 | X | + | 240 | X | X | + | 45 |
| = | 60 | X | + | 120 | X | + | 240 | X | X | + | 45 |
| = | 180 | X | + | 240 | X | X | + | 45 |
| 180 | X | + | 240 | X | X | + | 45 | = | 195 |
| X1= | - | 5 4 |
| X2= | 1 2 |