| 660000 | = | 1000 | ( | 1 | + | 1 200 | x | ) | × | 500 | ( | 1 | + | 1 100 | x | ) |
| Right side of the equation = | 500000 | ( | 1 | + | 1 200 | x | ) | ( | 1 | + | 1 100 | x | ) |
| 660000 | = | 500000 | ( | 1 | + | 1 200 | x | ) | ( | 1 | + | 1 100 | x | ) |
| Right side of the equation = | 500000 | × | 1 | ( | 1 | + | 1 100 | x | ) | + | 500000 | × | 1 200 | x | ( | 1 | + | 1 100 | x | ) |
| = | 500000 | ( | 1 | + | 1 100 | x | ) | + | 2500 | x | ( | 1 | + | 1 100 | x | ) |
| = | 500000 | × | 1 | + | 500000 | × | 1 100 | x | + | 2500 | x | ( | 1 | + | 1 100 | x | ) |
| = | 500000 | + | 5000 | x | + | 2500 | x | ( | 1 | + | 1 100 | x | ) |
| = | 500000 | + | 5000 | x | + | 2500 | x | × | 1 | + | 2500 | x | × | 1 100 | x |
| = | 500000 | + | 5000 | x | + | 2500 | x | + | 25 | x | x |
| = | 500000 | + | 7500 | x | + | 25 | x | x |
| 660000 | = | 500000 | + | 7500 | x | + | 25 | x | x |