| ( | 80 | − | X | ) | ( | 400 | + | 14400 | X | ) | = | 122000 |
| Left side of the equation = | 80 | ( | 400 | + | 14400 | X | ) | − | X | ( | 400 | + | 14400 | X | ) |
| = | 80 | × | 400 | + | 80 | × | 14400 | X | − | X | ( | 400 | + | 14400 | X | ) |
| = | 32000 | + | 1152000 | X | − | X | ( | 400 | + | 14400 | X | ) |
| = | 32000 | + | 1152000 | X | − | X | × | 400 | − | X | × | 14400 | X |
| = | 32000 | + | 1151600 | X | − | X | × | 14400 | X |
| 32000 | + | 1151600 | X | − | X | × | 14400 | X | = | 122000 |