| ( | X | − | 600 | × | 12 100 | ) | ( | 1 | − | 30 100 | ) | ÷ | ( | 100 | + | 50 | ) | = | ( | X | − | 1350 | × | 12 100 | ) | ( | 1 | − | 30 100 | ) | ÷ | 100 |
| 方程两边同时乘以: | ( | 100 | + | 50 | ) |
| ( | X | − | 600 | × | 12 100 | ) | ( | 1 | − | 30 100 | ) | = | ( | X | − | 1350 | × | 12 100 | ) | ( | 1 | − | 30 100 | ) | ÷ | 100 | × | ( | 100 | + | 50 | ) |
| X | ( | 1 | − | 30 100 | ) | − | 600 | × | 12 100 | ( | 1 | − | 30 100 | ) | = | ( | X | − | 1350 | × | 12 100 | ) | ( | 1 | − | 30 100 | ) | ÷ | 100 | × | ( | 100 | + | 50 | ) |
| X | ( | 1 | − | 30 100 | ) | − | 600 | × | 12 100 | ( | 1 | − | 30 100 | ) | = | X | ( | 1 | − | 30 100 | ) | ÷ | 100 | × | ( | 100 | + | 50 | ) | − | 1350 | × | 12 100 | ( | 1 | − | 30 100 | ) | ÷ | 100 | × | ( | 100 | + | 50 | ) |
| X | ( | 1 | − | 30 100 | ) | − | 72 | ( | 1 | − | 30 100 | ) | = | X | ( | 1 | − | 30 100 | ) | × | 1 100 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
| X | × | 1 | − | X | × | 30 100 | − | 72 | ( | 1 | − | 30 100 | ) | = | X | ( | 1 | − | 30 100 | ) | × | 1 100 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
| X | × | 1 | − | X | × | 30 100 | − | 72 | ( | 1 | − | 30 100 | ) | = | X | × | 1 | × | 1 100 | ( | 100 | + | 50 | ) | − | X | × | 30 100 | × | 1 100 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
| X | × | 1 | − | X | × | 30 100 | − | 72 | ( | 1 | − | 30 100 | ) | = | X | × | 1 100 | ( | 100 | + | 50 | ) | − | X | × | 3 1000 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 72 | ( | 1 | − | 30 100 | ) | = | X | × | 1 100 | ( | 100 | + | 50 | ) | − | X | × | 3 1000 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 72 | × | 1 | + | 72 | × | 30 100 | = | X | × | 1 100 | ( | 100 | + | 50 | ) | − | X | × | 3 1000 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 72 | × | 1 | + | 72 | × | 30 100 | = | X | × | 1 100 | × | 100 | + | X | × | 1 100 | × | 50 | − | X | × | 3 1000 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 72 | + | 108 5 | = | X | × | 1 | + | X | × | 1 2 | − | X | × | 3 1000 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 3 2 | X | − | X | × | 3 1000 | ( | 100 | + | 50 | ) | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 3 2 | X | − | X | × | 3 1000 | × | 100 | − | X | × | 3 1000 | × | 50 | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 3 2 | X | − | X | × | 3 10 | − | X | × | 3 20 | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 81 50 | ( | 1 | − | 30 100 | ) | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 81 50 | × | 1 | ( | 100 | + | 50 | ) | + | 81 50 | × | 30 100 | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 81 50 | ( | 100 | + | 50 | ) | + | 243 500 | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 81 50 | × | 100 | − | 81 50 | × | 50 | + | 243 500 | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 162 | − | 81 | + | 243 500 | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 243 | + | 243 500 | ( | 100 | + | 50 | ) |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 243 | + | 243 500 | × | 100 | + | 243 500 | × | 50 |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 243 | + | 243 5 | + | 243 10 |
7 10 | X | − | 252 5 | = | 21 20 | X | − | 1701 10 |
7 10 | X | − | 21 20 | X | = | - | 1701 10 | + | 252 5 |
| - | 7 20 | X | = | - | 1701 10 | + | 252 5 |
| - | 7 20 | X | = | - | 1197 10 |
1197 10 | = | 7 20 | X |
7 20 | X | = | 1197 10 |
| X | = | 1197 10 | ÷ | 7 20 |
| = | 1197 10 | × | 20 7 |
| = | 171 | × | 2 |
| X | = | 342 |