| ( | 200 | + | x | ) | ( | 64 | − | 10 | x | ) | = | 14400 |
| Left side of the equation = | 200 | ( | 64 | − | 10 | x | ) | + | x | ( | 64 | − | 10 | x | ) |
| = | 200 | × | 64 | − | 200 | × | 10 | x | + | x | ( | 64 | − | 10 | x | ) |
| = | 12800 | − | 2000 | x | + | x | ( | 64 | − | 10 | x | ) |
| = | 12800 | − | 2000 | x | + | x | × | 64 | − | x | × | 10 | x |
| = | 12800 | − | 1936 | x | − | x | × | 10 | x |
| 12800 | − | 1936 | x | − | x | × | 10 | x | = | 14400 |