| ( | 80 | − | 50 | ) | × | 40 | + | 80 | × | 25 100 | ( | 60 | − | x | ) | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) | = | 2200 |
| Left side of the equation = | ( | 80 | − | 50 | ) | × | 40 | + | 20 | ( | 60 | − | x | ) | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) |
| ( | 80 | − | 50 | ) | × | 40 | + | 20 | ( | 60 | − | x | ) | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) | = | 2200 |
| Left side of the equation = | 80 | × | 40 | − | 50 | × | 40 | + | 20 | ( | 60 | − | x | ) | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) |
| = | 3200 | − | 2000 | + | 20 | ( | 60 | − | x | ) | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) |
| = | 1200 | + | 20 | ( | 60 | − | x | ) | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) |
| = | 1200 | + | 20 | × | 60 | − | 20 | x | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) |
| = | 1200 | + | 1200 | − | 20 | x | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) |
| = | 2400 | − | 20 | x | + | x | ( | 9 10 | ( | 80 | × | 125 100 | ) | − | 80 | ) |
| = | 2400 | − | 20 | x | + | x | × | 9 10 | ( | 80 | × | 125 100 | ) | − | x | × | 80 |
| = | 2400 | − | 100 | x | + | x | × | 9 10 | ( | 80 | × | 125 100 | ) |
| = | 2400 | − | 100 | x | + | x | × | 9 10 | × | 80 | × | 125 100 |
| = | 2400 | − | 100 | x | + | x | × | 90 |
| = | 2400 | − | 10 | x |
| 2400 | − | 10 | x | = | 2200 |
| - | 10 | x | = | 2200 | − | 2400 |
| - | 10 | x | = | - | 200 |
| 200 | = | 10 | x |
| 10 | x | = | 200 |
| x | = | 200 | ÷ | 10 |
| = | 200 | × | 1 10 |
| = | 20 | × | 1 |
| x | = | 20 |