( | 1 | + | 30 100 | ) | x | × | 90 100 | + | ( | 300 | − | x | ) | × | 120 100 | × | 90 100 | − | 300 | = | 42 |
方程左边 = | ( | 1 | + | 30 100 | ) | x | × | 90 100 | + | ( | 300 | − | x | ) | × | 27 25 | − | 300 |
( | 1 | + | 30 100 | ) | x | × | 90 100 | + | ( | 300 | − | x | ) | × | 27 25 | − | 300 | = | 42 |
方程左边 = | 1 | x | × | 90 100 | + | 30 100 | x | × | 90 100 | + | ( | 300 | − | x | ) | × | 27 25 | − | 300 |
= | 9 10 | x | + | 27 100 | x | + | ( | 300 | − | x | ) | × | 27 25 | − | 300 |
= | 117 100 | x | + | ( | 300 | − | x | ) | × | 27 25 | − | 300 |
= | 117 100 | x | + | 300 | × | 27 25 | − | x | × | 27 25 | − | 300 |
= | 117 100 | x | + | 324 | − | x | × | 27 25 | − | 300 |
= | 9 100 | x | + | 24 |
9 100 | x | + | 24 | = | 42 |
9 100 | x | = | 42 | − | 24 |
9 100 | x | = | 18 |
x | = | 18 | ÷ | 9 100 |
= | 18 | × | 100 9 |
= | 2 | × | 100 |
x | = | 200 |