( | y | − | 750 | ) | ( | 250 | − | 1 | ÷ | 5 | × | y | ) | = | 12000 |
方程左边 = | y | ( | 250 | − | 1 | ÷ | 5 | × | y | ) | − | 750 | ( | 250 | − | 1 | ÷ | 5 | × | y | ) |
= | y | × | 250 | − | y | × | 1 | ÷ | 5 | × | y | − | 750 | ( | 250 | − | 1 | ÷ | 5 | × | y | ) |
= | y | × | 250 | − | y | × | 1 5 | y | − | 750 | ( | 250 | − | 1 | ÷ | 5 | × | y | ) |
= | 250 | y | − | y | × | 1 5 | y | − | 750 | × | 250 | + | 750 | × | 1 | ÷ | 5 | × | y |
= | 250 | y | − | y | × | 1 5 | y | − | 187500 | + | 150 | y |
= | 400 | y | − | y | × | 1 5 | y | − | 187500 |
400 | y | − | y | × | 1 5 | y | − | 187500 | = | 12000 |