| 31500 | + | ( | 2500 | + | 125 | ÷ | 2 | × | a | ) | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | − | 44000 | − | 200 | a | = | 0 |
| 方程左边 = | - | 12500 | + | ( | 2500 | + | 125 | ÷ | 2 | × | a | ) | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | − | 200 | a |
| - | 12500 | + | ( | 2500 | + | 125 | ÷ | 2 | × | a | ) | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | − | 200 | a | = | 0 |
| 方程左边 = | - | 12500 | + | 2500 | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | + | 125 | ÷ | 2 | × | a | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | − | 200 | a |
| = | - | 12500 | + | 2500 | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | + | 125 2 | a | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | − | 200 | a |
| = | - | 12500 | + | 2500 | × | 5 | − | 2500 | × | 3 | ÷ | 80 | × | a | + | 125 2 | a | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | − | 200 | a |
| = | - | 12500 | + | 12500 | − | 375 4 | a | + | 125 2 | a | ( | 5 | − | 3 | ÷ | 80 | × | a | ) | − | 200 | a |
| = | - | 0 | − | 1175 4 | a | + | 125 2 | a | ( | 5 | − | 3 | ÷ | 80 | × | a | ) |
| = | - | 1175 4 | a | + | 125 2 | a | × | 5 | − | 125 2 | a | × | 3 | ÷ | 80 | × | a |
| = | - | 1175 4 | a | + | 625 2 | a | − | 75 32 | a | a |
| = | 75 4 | a | − | 75 32 | a | a |
75 4 | a | − | 75 32 | a | a | = | 0 |