| 50 | + | 40 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) | = | 81 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| Left side of the equation = | 50 | + | 40 | × | 1 | ( | 1 | + | x | ) | + | 40 | x | ( | 1 | + | x | ) | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 50 | + | 40 | ( | 1 | + | x | ) | + | 40 | x | ( | 1 | + | x | ) | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 50 | + | 40 | × | 1 | + | 40 | x | + | 40 | x | ( | 1 | + | x | ) | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 50 | + | 40 | + | 40 | x | + | 40 | x | ( | 1 | + | x | ) | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 90 | + | 40 | x | + | 40 | x | ( | 1 | + | x | ) | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 90 | + | 40 | x | + | 40 | x | × | 1 | + | 40 | x | x | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 90 | + | 40 | x | + | 40 | x | + | 40 | x | x | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 90 | + | 80 | x | + | 40 | x | x | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | ( | 1 | + | x | ) |
| = | 90 | + | 80 | x | + | 40 | x | x | + | 20 | × | 1 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | + | 20 | x |
| = | 90 | + | 80 | x | + | 40 | x | x | + | 20 | ( | 1 | + | x | ) | ( | 1 | + | x | ) | + | 20 | x | ( | 1 | + | x | ) |
| = | 90 | + | 80 | x | + | 40 | x | x | + | 20 | × | 1 | ( | 1 | + | x | ) | + | 20 | x | ( | 1 | + | x | ) |
| = | 90 | + | 80 | x | + | 40 | x | x | + | 20 | ( | 1 | + | x | ) | + | 20 | x | ( | 1 | + | x | ) | + | 20 |
| = | 90 | + | 80 | x | + | 40 | x | x | + | 20 | × | 1 | + | 20 | x | + | 20 | x |
| = | 90 | + | 80 | x | + | 40 | x | x | + | 20 | + | 20 | x | + | 20 | x | ( | 1 | + | x | ) |
| = | 110 | + | 100 | x | + | 40 | x | x | + | 20 | x | ( | 1 | + | x | ) | + | 20 | x | ( | 1 | + | x | ) |
| = | 110 | + | 100 | x | + | 40 | x | x | + | 20 | x | × | 1 | + | 20 | x | x |
| = | 110 | + | 100 | x | + | 40 | x | x | + | 20 | x | + | 20 | x | x | + | 20 |
| = | 110 | + | 120 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | ( | 1 | + | x | ) |
| = | 110 | + | 120 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | × | 1 |
| = | 110 | + | 120 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | ( | 1 | + | x | ) |
| = | 110 | + | 120 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | × | 1 |
| = | 110 | + | 120 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | + | 20 |
| = | 110 | + | 140 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | x |
| = | 110 | + | 140 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | x |
| = | 110 | + | 140 | x | + | 40 | x | x | + | 20 | x | x | + | 20 | x | x |