| ( | x | + | 3 10 | ) | ( | 200 | ( | x | − | 1 20 | ) | + | 500 | ) | = | 180 |
| Left side of the equation = | x | ( | 200 | ( | x | − | 1 20 | ) | + | 500 | ) | + | 3 10 | ( | 200 | ( | x | − | 1 20 | ) | + | 500 | ) |
| = | x | × | 200 | ( | x | − | 1 20 | ) | + | x | × | 500 | + | 3 10 | ( | 200 | ( | x | − | 1 20 | ) | + | 500 | ) |
| = | x | × | 200 | x | − | x | × | 200 | × | 1 20 | + | 500 | x | + | 3 10 | ( | 200 | ( | x | − | 1 20 | ) | + | 500 | ) |
| = | x | × | 200 | x | − | x | × | 10 | + | 500 | x | + | 3 10 | ( | 200 | ( | x | − | 1 20 | ) | + | 500 | ) |
| = | x | × | 200 | x | + | 490 | x | + | 3 10 | ( | 200 | ( | x | − | 1 20 | ) | + | 500 | ) |
| = | x | × | 200 | x | + | 490 | x | + | 3 10 | × | 200 | ( | x | − | 1 20 | ) | + | 3 10 | × | 500 |
| = | x | × | 200 | x | + | 490 | x | + | 60 | ( | x | − | 1 20 | ) | + | 150 |
| = | x | × | 200 | x | + | 490 | x | + | 60 | x | − | 60 | × | 1 20 | + | 150 |
| = | x | × | 200 | x | + | 490 | x | + | 60 | x | − | 3 | + | 150 |
| = | x | × | 200 | x | + | 550 | x | + | 147 |
| x | × | 200 | x | + | 550 | x | + | 147 | = | 180 |