| ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 20 100 | − | 16920 | ) | − | ( | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | − | 1410 | ) | × | 12 | = | 4000 |
| 方程左边 = | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 20 100 | − | 16920 | − | ( | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | − | 1410 | ) | × | 12 |
| = | X | × | 12 | × | 20 100 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | × | 20 100 | − | 16920 | − | ( | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | − | 1410 | ) | × | 12 |
| = | X | × | 12 5 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 5 | − | 16920 | − | ( | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | − | 1410 | ) | × | 12 |
| = | 12 5 | X | − | 5000 | × | 12 5 | − | 1500 | × | 12 5 | − | 2000 | × | 12 5 | − | 16920 | − | ( | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | − | 1410 | ) | × | 12 |
| = | 12 5 | X | − | 12000 | − | 3600 | − | 4800 | − | 16920 | − | ( | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | − | 1410 | ) | × | 12 |
| = | 12 5 | X | − | 37320 | − | ( | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | − | 1410 | ) | × | 12 |
| = | 12 5 | X | − | 37320 | − | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 10 100 | × | 12 | + | 1410 | × | 12 |
| = | 12 5 | X | − | 37320 | − | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 6 5 | + | 16920 |
| = | 12 5 | X | − | 20400 | − | ( | X | − | ( | 5000 | + | 1500 | + | 2000 | ) | ) | × | 6 5 |
| = | 12 5 | X | − | 20400 | − | X | × | 6 5 | + | ( | 5000 | + | 1500 | + | 2000 | ) | × | 6 5 |
| = | 6 5 | X | − | 20400 | + | ( | 5000 | + | 1500 | + | 2000 | ) | × | 6 5 |
| = | 6 5 | X | − | 20400 | + | 5000 | × | 6 5 | + | 1500 | × | 6 5 | + | 2000 | × | 6 5 |
| = | 6 5 | X | − | 20400 | + | 6000 | + | 1800 | + | 2400 |
| = | 6 5 | X | − | 10200 |
6 5 | X | − | 10200 | = | 4000 |
6 5 | X | = | 4000 | + | 10200 |
6 5 | X | = | 14200 |
| X | = | 14200 | ÷ | 6 5 |
| = | 14200 | × | 5 6 |
| = | 7100 | × | 5 3 |
| X | = | 35500 3 |
| X | = | 11833.333333 |