| 20 | X | + | 25 | ( | 200 | − | X | ) | + | 15 | ( | 220 | − | X | ) | + | 22 | ( | 80 | + | X | ) | = | 10200 |
| Left side of the equation = | 20 | X | + | 25 | × | 200 | − | 25 | X | + | 15 | ( | 220 | − | X | ) | + | 22 | ( | 80 | + | X | ) |
| = | 20 | X | + | 5000 | − | 25 | X | + | 15 | ( | 220 | − | X | ) | + | 22 | ( | 80 | + | X | ) |
| = | - | 5 | X | + | 5000 | + | 15 | ( | 220 | − | X | ) | + | 22 | ( | 80 | + | X | ) |
| = | - | 5 | X | + | 5000 | + | 15 | × | 220 | − | 15 | X | + | 22 | ( | 80 | + | X | ) |
| = | - | 5 | X | + | 5000 | + | 3300 | − | 15 | X | + | 22 | ( | 80 | + | X | ) |
| = | - | 20 | X | + | 8300 | + | 22 | ( | 80 | + | X | ) |
| = | - | 20 | X | + | 8300 | + | 22 | × | 80 | + | 22 | X |
| = | - | 20 | X | + | 8300 | + | 1760 | + | 22 | X |
| = | 2 | X | + | 10060 |
| 2 | X | + | 10060 | = | 10200 |
| 2 | X | = | 10200 | − | 10060 |
| 2 | X | = | 140 |
| X | = | 140 | ÷ | 2 |
| = | 140 | × | 1 2 |
| = | 70 | × | 1 |
| X | = | 70 |