| ( | 200 | − | y | ) | ( | 64 | − | y | ÷ | 10 | ) | = | 14400 |
| Left side of the equation = | 200 | ( | 64 | − | y | ÷ | 10 | ) | − | y | ( | 64 | − | y | ÷ | 10 | ) |
| = | 200 | × | 64 | − | 200 | y | ÷ | 10 | − | y | ( | 64 | − | y | ÷ | 10 | ) |
| = | 12800 | − | 20 | y | − | y | ( | 64 | − | y | ÷ | 10 | ) |
| = | 12800 | − | 20 | y | − | y | × | 64 | + | y | y | ÷ | 10 |
| = | 12800 | − | 84 | y | + | y | y | × | 1 10 |
| 12800 | − | 84 | y | + | y | y | × | 1 10 | = | 14400 |