| ( | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | − | 40 | × | 50 | ) | × | 30 | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 | = | 642000 |
| Left side of the equation = | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 30 | − | 40 | × | 50 | × | 30 | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 30 | − | 60000 | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 50 | ( | 40 | + | 2 | x | ) | × | 30 | + | 3 | x | ( | 40 | + | 2 | x | ) | × | 30 | − | 60000 | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 1500 | ( | 40 | + | 2 | x | ) | + | 90 | x | ( | 40 | + | 2 | x | ) | − | 60000 | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 1500 | × | 40 | + | 1500 | × | 2 | x | + | 90 | x | ( | 40 | + | 2 | x | ) | − | 60000 | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 60000 | + | 3000 | x | + | 90 | x | ( | 40 | + | 2 | x | ) | − | 60000 | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 0 | + | 3000 | x | + | 90 | x | ( | 40 | + | 2 | x | ) | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 0 | + | 3000 | x | + | 90 | x | × | 40 | + | 90 | x | × | 2 | x | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) |
| = | 0 | + | 3000 | x | + | 3600 | x | + | 180 | x | x | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 0 | + | 6600 | x | + | 180 | x | x | + | ( | 50 | + | 3 | x | ) | ( | 40 | + | 2 | x | ) | × | 100 |
| = | 0 | + | 6600 | x | + | 180 | x | x | + | 50 | ( | 40 | + | 2 | x | ) | × | 100 | + | 3 | x | ( | 40 | + | 2 | x | ) |
| = | 0 | + | 6600 | x | + | 180 | x | x | + | 5000 | ( | 40 | + | 2 | x | ) | + | 300 | x | ( | 40 | + | 2 | x | ) |
| = | 0 | + | 6600 | x | + | 180 | x | x | + | 5000 | × | 40 | + | 5000 | × | 2 | x | + | 300 |
| = | 0 | + | 6600 | x | + | 180 | x | x | + | 200000 | + | 10000 | x | + | 300 | x | ( | 40 | + | 2 | x | ) |
| = | 200000 | + | 16600 | x | + | 180 | x | x | + | 300 | x | ( | 40 | + | 2 | x | ) |
| = | 200000 | + | 16600 | x | + | 180 | x | x | + | 300 | x | × | 40 | + | 300 | x | × | 2 |
| = | 200000 | + | 16600 | x | + | 180 | x | x | + | 12000 | x | + | 600 | x | x |
| = | 200000 | + | 28600 | x | + | 180 | x | x | + | 600 | x | x |
| 200000 | + | 28600 | x | + | 180 | x | x | + | 600 | x | x | = | 642000 |