9 10 | ( | 1200 | − | x | ) | + | 200 | + | 17 20 | ( | x | − | 200 | ) | = | 1098 |
| Left side of the equation = | 9 10 | × | 1200 | − | 9 10 | x | + | 200 | + | 17 20 | ( | x | − | 200 | ) |
| = | 1080 | − | 9 10 | x | + | 200 | + | 17 20 | ( | x | − | 200 | ) |
| = | 1280 | − | 9 10 | x | + | 17 20 | ( | x | − | 200 | ) |
| = | 1280 | − | 9 10 | x | + | 17 20 | x | − | 17 20 | × | 200 |
| = | 1280 | − | 9 10 | x | + | 17 20 | x | − | 170 |
| = | 1110 | − | 1 20 | x |
| 1110 | − | 1 20 | x | = | 1098 |
| - | 1 20 | x | = | 1098 | − | 1110 |
| - | 1 20 | x | = | - | 12 |
| 12 | = | 1 20 | x |
1 20 | x | = | 12 |
| x | = | 12 | ÷ | 1 20 |
| = | 12 | × | 20 |
| x | = | 240 |