| ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 20 100 | − | 2520 | ) | − | ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | − | 1410 | ) | = | 4000 |
| Left side of the equation = | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 20 100 | − | 2520 | − | ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | − | 1410 | ) |
| = | X | × | 12 | × | 20 100 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | × | 20 100 | − | 2520 | − | ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | − | 1410 | ) |
| = | X | × | 12 5 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 5 | − | 2520 | − | ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | − | 1410 | ) |
| = | 12 5 | X | − | 5000 | × | 12 5 | − | 1500 | × | 12 5 | − | 2000 | × | 12 5 | − | 2520 | − | ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | − | 1410 | ) |
| = | 12 5 | X | − | 12000 | − | 3600 | − | 4800 | − | 2520 | − | ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | − | 1410 | ) |
| = | 12 5 | X | − | 22920 | − | ( | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | − | 1410 | ) |
| = | 12 5 | X | − | 22920 | − | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 | + | 1410 |
| = | 12 5 | X | − | 21510 | − | ( | X | × | 12 | − | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | ) | × | 10 100 |
| = | 12 5 | X | − | 21510 | − | X | × | 12 | × | 10 100 | + | ( | 5000 | + | 1500 | + | 2000 | ) | × | 12 | × | 10 100 |
| = | 12 5 | X | − | 21510 | − | X | × | 6 5 | + | ( | 5000 | + | 1500 | + | 2000 | ) | × | 6 5 |
| = | 6 5 | X | − | 21510 | + | ( | 5000 | + | 1500 | + | 2000 | ) | × | 6 5 |
| = | 6 5 | X | − | 21510 | + | 5000 | × | 6 5 | + | 1500 | × | 6 5 | + | 2000 | × | 6 5 |
| = | 6 5 | X | − | 21510 | + | 6000 | + | 1800 | + | 2400 |
| = | 6 5 | X | − | 11310 |
6 5 | X | − | 11310 | = | 4000 |
6 5 | X | = | 4000 | + | 11310 |
6 5 | X | = | 15310 |
| X | = | 15310 | ÷ | 6 5 |
| = | 15310 | × | 5 6 |
| = | 7655 | × | 5 3 |
| X | = | 38275 3 |
| X | = | 12758.333333 |