| ( | 28 | − | 2 | y | ) | ( | 460 | + | 4 | y | ) | = | 2880 |
| Left side of the equation = | 28 | ( | 460 | + | 4 | y | ) | − | 2 | y | ( | 460 | + | 4 | y | ) |
| = | 28 | × | 460 | + | 28 | × | 4 | y | − | 2 | y | ( | 460 | + | 4 | y | ) |
| = | 12880 | + | 112 | y | − | 2 | y | ( | 460 | + | 4 | y | ) |
| = | 12880 | + | 112 | y | − | 2 | y | × | 460 | − | 2 | y | × | 4 | y |
| = | 12880 | + | 112 | y | − | 920 | y | − | 8 | y | y |
| = | 12880 | − | 808 | y | − | 8 | y | y |
| 12880 | − | 808 | y | − | 8 | y | y | = | 2880 |