| ( | 25 100 | X | + | 70 | ) | ÷ | X | = | 3 | ÷ | ( | 3 | + | 2 | ) |
| 方程两边同时乘以: | X | , | ( | 3 | + | 2 | ) |
| ( | 25 100 | X | + | 70 | ) | ( | 3 | + | 2 | ) | = | 3 | X |
25 100 | X | ( | 3 | + | 2 | ) | + | 70 | ( | 3 | + | 2 | ) | = | 3 | X |
25 100 | X | × | 3 | + | 25 100 | X | × | 2 | + | 70 | ( | 3 | + | 2 | ) | = | 3 | X |
3 4 | X | + | 1 2 | X | + | 70 | ( | 3 | + | 2 | ) | = | 3 | X |
5 4 | X | + | 70 | ( | 3 | + | 2 | ) | = | 3 | X |
5 4 | X | + | 70 | × | 3 | + | 70 | × | 2 | = | 3 | X |
5 4 | X | + | 210 | + | 140 | = | 3 | X |
5 4 | X | + | 350 | = | 3 | X |
5 4 | X | − | 3 | X | = | - | 350 |
| - | 7 4 | X | = | - | 350 |
| 350 | = | 7 4 | X |
7 4 | X | = | 350 |
| X | = | 350 | ÷ | 7 4 |
| = | 350 | × | 4 7 |
| = | 50 | × | 4 |
| X | = | 200 |