| ( | 10 | x | + | x | ) | + | ( | 200 | − | x | ) | × | 10 | × | 90 100 | = | 1960 |
| Left side of the equation = | ( | 10 | x | + | x | ) | + | ( | 200 | − | x | ) | × | 9 |
| ( | 10 | x | + | x | ) | + | ( | 200 | − | x | ) | × | 9 | = | 1960 |
| Left side of the equation = | 10 | x | + | x | + | ( | 200 | − | x | ) | × | 9 |
| = | 11 | x | + | ( | 200 | − | x | ) | × | 9 |
| = | 11 | x | + | 200 | × | 9 | − | x | × | 9 |
| = | 11 | x | + | 1800 | − | x | × | 9 |
| = | 2 | x | + | 1800 |
| 2 | x | + | 1800 | = | 1960 |
| 2 | x | = | 1960 | − | 1800 |
| 2 | x | = | 160 |
| x | = | 160 | ÷ | 2 |
| = | 160 | × | 1 2 |
| = | 80 | × | 1 |
| x | = | 80 |