( | x | × | 40 | − | 120 | − | 20 | ) | × | 3 4 | ÷ | 20 | = | 0 |
方程左边 = | ( | x | × | 40 | − | 120 | − | 20 | ) | × | 3 80 |
( | x | × | 40 | − | 120 | − | 20 | ) | × | 3 80 | = | 0 |
方程左边 = | x | × | 40 | × | 3 80 | − | 120 | × | 3 80 | − | 20 | × | 3 80 |
= | x | × | 3 2 | − | 9 2 | − | 3 4 |
= | 3 2 | x | − | 21 4 |
3 2 | x | − | 21 4 | = | 0 |
3 2 | x | = | 0 | + | 21 4 |
3 2 | x | = | 21 4 |
x | = | 21 4 | ÷ | 3 2 |
= | 21 4 | × | 2 3 |
= | 7 2 | × | 1 |
x | = | 7 2 |
x | = | 3.5 |