| ( | 100 | + | 1 | ÷ | 2 | × | y | ) | ( | 280 | − | y | ) | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) | = | 99200 |
| 方程左边 = | 100 | ( | 280 | − | y | ) | + | 1 | ÷ | 2 | × | y | ( | 280 | − | y | ) | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) |
| = | 100 | ( | 280 | − | y | ) | + | 1 2 | y | ( | 280 | − | y | ) | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) |
| = | 100 | × | 280 | − | 100 | y | + | 1 2 | y | ( | 280 | − | y | ) | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) |
| = | 28000 | − | 100 | y | + | 1 2 | y | ( | 280 | − | y | ) | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) |
| = | 28000 | − | 100 | y | + | 1 2 | y | × | 280 | − | 1 2 | y | y | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) |
| = | 28000 | − | 100 | y | + | 140 | y | − | 1 2 | y | y | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) |
| = | 28000 | + | 40 | y | − | 1 2 | y | y | + | 320 | ( | 200 | + | 1 | ÷ | 4 | × | y | ) |
| = | 28000 | + | 40 | y | − | 1 2 | y | y | + | 320 | × | 200 | + | 320 | × | 1 | ÷ | 4 | × | y |
| = | 28000 | + | 40 | y | − | 1 2 | y | y | + | 64000 | + | 80 | y |
| = | 92000 | + | 120 | y | − | 1 2 | y | y |
| 92000 | + | 120 | y | − | 1 2 | y | y | = | 99200 |