| ( | 8 | − | a | ) | ( | 200 | + | 100 | a | ) | + | 150 | ( | 6 | − | a | ) | = | 3000 |
| 方程左边 = | 8 | ( | 200 | + | 100 | a | ) | − | a | ( | 200 | + | 100 | a | ) | + | 150 | ( | 6 | − | a | ) |
| = | 8 | × | 200 | + | 8 | × | 100 | a | − | a | ( | 200 | + | 100 | a | ) | + | 150 | ( | 6 | − | a | ) |
| = | 1600 | + | 800 | a | − | a | ( | 200 | + | 100 | a | ) | + | 150 | ( | 6 | − | a | ) |
| = | 1600 | + | 800 | a | − | a | × | 200 | − | a | × | 100 | a | + | 150 | ( | 6 | − | a | ) |
| = | 1600 | + | 600 | a | − | a | × | 100 | a | + | 150 | ( | 6 | − | a | ) |
| = | 1600 | + | 600 | a | − | a | × | 100 | a | + | 150 | × | 6 | − | 150 | a |
| = | 1600 | + | 600 | a | − | a | × | 100 | a | + | 900 | − | 150 | a |
| = | 2500 | + | 450 | a | − | a | × | 100 | a |
| 2500 | + | 450 | a | − | a | × | 100 | a | = | 3000 |
| a2= | 5 2 |