| ( | 20 | + | 2 | x | ) | ( | 16 | + | 2 | x | ) | = | 480 |
| Left side of the equation = | 20 | ( | 16 | + | 2 | x | ) | + | 2 | x | ( | 16 | + | 2 | x | ) |
| = | 20 | × | 16 | + | 20 | × | 2 | x | + | 2 | x | ( | 16 | + | 2 | x | ) |
| = | 320 | + | 40 | x | + | 2 | x | ( | 16 | + | 2 | x | ) |
| = | 320 | + | 40 | x | + | 2 | x | × | 16 | + | 2 | x | × | 2 | x |
| = | 320 | + | 40 | x | + | 32 | x | + | 4 | x | x |
| = | 320 | + | 72 | x | + | 4 | x | x |
| 320 | + | 72 | x | + | 4 | x | x | = | 480 |