| 80 | x | ÷ | ( | 64 | × | 2 25 | x | + | 32 | ( | 1 | ÷ | 31 | × | x | ) | ÷ | 21 100 | + | 80 | x | ) | = | 1 20 |
| 方程两边同时乘以: | ( | 64 | × | 2 25 | x | + | 32 | ( | 1 | ÷ | 31 | × | x | ) | ÷ | 21 100 | + | 80 | x | ) |
| 80 | x | = | 1 20 | ( | 64 | × | 2 25 | x | + | 32 | ( | 1 | ÷ | 31 | × | x | ) | ÷ | 21 100 | + | 80 | x | ) |
| 80 | x | = | 1 20 | × | 64 | × | 2 25 | x | + | 1 20 | × | 32 | ( | 1 | ÷ | 31 | × | x | ) | ÷ | 21 100 | + | 1 20 | × | 80 | x |
| 80 | x | = | 32 125 | x | + | 160 21 | ( | 1 | ÷ | 31 | × | x | ) | + | 4 | x |
| 80 | x | = | 532 125 | x | + | 160 21 | ( | 1 | ÷ | 31 | × | x | ) |
| 80 | x | = | 532 125 | x | + | 160 21 | × | 1 | ÷ | 31 | × | x |
| 80 | x | = | 532 125 | x | + | 160 651 | x |
| 80 | x | = | 366332 81375 | x |
| 80 | x | − | 366332 81375 | x | = | 0 |
6143668 81375 | x | = | 0 |
| x | = | 0 | ÷ | 6143668 81375 |
| = | 0 | × | 81375 6143668 |
| x | = | 0 |
| x | = | 0 |