| 160 | x | + | ( | 190 | − | 160 | ) | ( | x | + | 3 20 | ) | = | 90 |
| Left side of the equation = | 160 | x | + | 190 | ( | x | + | 3 20 | ) | − | 160 | ( | x | + | 3 20 | ) |
| = | 160 | x | + | 190 | x | + | 190 | × | 3 20 | − | 160 | ( | x | + | 3 20 | ) |
| = | 160 | x | + | 190 | x | + | 57 2 | − | 160 | ( | x | + | 3 20 | ) |
| = | 350 | x | + | 57 2 | − | 160 | ( | x | + | 3 20 | ) |
| = | 350 | x | + | 57 2 | − | 160 | x | − | 160 | × | 3 20 |
| = | 350 | x | + | 57 2 | − | 160 | x | − | 24 |
| = | 190 | x | + | 9 2 |
| 190 | x | + | 9 2 | = | 90 |
| 190 | x | = | 90 | − | 9 2 |
| 190 | x | = | 171 2 |
| x | = | 171 2 | ÷ | 190 |
| = | 171 2 | × | 1 190 |
| x | = | 171 380 |
| x | = | 9 20 |
| x | = | 0.45 |