| 90 | ( | 10000 | ÷ | x | ) | + | 110 | ( | 10000 | ÷ | 90 | − | 10000 | ÷ | x | ) | + | 60 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 60 | ) | + | 80 | ( | 30000 | ÷ | x | − | 20000 | ÷ | x | ) | + | 100 | ( | 10000 | ÷ | x | ) | = | 30000 |
| 90 | × | 10000 | ÷ | x | + | 110 | ( | 10000 | ÷ | 90 | − | 10000 | ÷ | x | ) | + | 60 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 60 | ) | + | 80 | ( | 30000 | ÷ | x | − | 20000 | ÷ | x | ) | + | 100 | ( | 10000 | ÷ | x | ) | = | 30000 |
| 900000 | ÷ | x | + | 110 | ( | 10000 | ÷ | 90 | − | 10000 | ÷ | x | ) | + | 60 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 60 | ) | + | 80 | ( | 30000 | ÷ | x | − | 20000 | ÷ | x | ) | + | 100 | ( | 10000 | ÷ | x | ) | = | 30000 |
| 方程两边同时乘以: | x |
| 900000 | + | 110 | ( | 10000 | ÷ | 90 | − | 10000 | ÷ | x | ) | x | + | 60 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 60 | ) | x | + | 80 | ( | 30000 | ÷ | x | − | 20000 | ÷ | x | ) | x | + | 100 | ( | 10000 | ÷ | 1 | ) | = | 30000 | x |
| 900000 | + | 110 | × | 10000 | ÷ | 90 | × | x | − | 110 | × | 10000 | ÷ | x | × | x | + | 60 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 60 | ) | x | = | 30000 | x |
| 900000 | + | 110000 9 | x | − | 1100000 | ÷ | x | × | x | + | 60 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 60 | ) | x | + | 80 | ( | 30000 | ÷ | x | − | 20000 | ÷ | x | ) | x | = | 30000 | x |
| 900000 | + | 110000 9 | x | − | 1100000 | ÷ | 1 | × | 1 | + | 60 | × | 20000 | ÷ | x | × | x | − | 60 | × | 10000 | = | 30000 | x |
| 900000 | + | 110000 9 | x | − | 1100000 | + | 1200000 | ÷ | x | × | x | − | 10000 | x | + | 80 | ( | 30000 | ÷ | x | − | 20000 | ÷ | x | ) | x | = | 30000 | x |
| - | 200000 | + | 20000 9 | x | + | 1200000 | ÷ | x | × | x | + | 80 | ( | 30000 | ÷ | x | − | 20000 | ÷ | x | ) | x | + | 100 | ( | 10000 | ÷ | 1 | ) | = | 30000 | x |
| - | 200000 | + | 20000 9 | x | + | 1200000 | ÷ | 1 | × | 1 | + | 80 | × | 30000 | ÷ | x | × | x | − | 80 | × | 20000 | = | 30000 | x |
| - | 200000 | + | 20000 9 | x | + | 1200000 | + | 2400000 | ÷ | x | × | x | − | 1600000 | ÷ | x | × | x | + | 100 | ( | 10000 | ÷ | 1 | ) | = | 30000 | x |
| 1000000 | + | 20000 9 | x | + | 2400000 | ÷ | x | × | x | − | 1600000 | ÷ | x | × | x | + | 100 | ( | 10000 | ÷ | 1 | ) | = | 30000 | x |
| 1000000 | + | 20000 9 | x | + | 2400000 | ÷ | 1 | × | 1 | − | 1600000 | ÷ | 1 | × | 1 | + | 100 | × | 10000 | ÷ | 1 | = | 30000 | x |
| 1000000 | + | 20000 9 | x | + | 2400000 | − | 1600000 | + | 1000000 | = | 30000 | x |
| 2800000 | + | 20000 9 | x | = | 30000 | x |
20000 9 | x | − | 30000 | x | = | - | 2800000 |
| - | 250000 9 | x | = | - | 2800000 |
| 2800000 | = | 250000 9 | x |
250000 9 | x | = | 2800000 |
| x | = | 2800000 | ÷ | 250000 9 |
| = | 2800000 | × | 9 250000 |
| = | 56 | × | 9 5 |
| x | = | 504 5 |
| x | = | 100.8 |