| ( | 80 | − | 50 | ) | × | 200 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) | = | 9000 |
| Left side of the equation = | 80 | × | 200 | − | 50 | × | 200 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 16000 | − | 10000 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | 80 | ( | 200 | + | 10 | X | ) | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | 80 | × | 200 | + | 80 | × | 10 | X | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | 16000 | + | 800 | X | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 22000 | + | 800 | X | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 22000 | + | 800 | X | − | X | × | 200 | − | X | × | 10 | X | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 22000 | + | 600 | X | − | X | × | 10 | X | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 22000 | + | 600 | X | − | X | × | 10 | X | − | 50 | × | 200 | − | 50 | × | 10 | X | + | ( | 40 | − | 50 | ) |
| = | 22000 | + | 600 | X | − | X | × | 10 | X | − | 10000 | − | 500 | X | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | 40 | ( | 400 | − | 10 | X | ) | − | 50 | ( | 400 | − | 10 | X | ) |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | 40 | × | 400 | − | 40 | × | 10 | X | − | 50 |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | 16000 | − | 400 | X | − | 50 | ( | 400 | − | 10 | X | ) |
| = | 28000 | − | 300 | X | − | X | × | 10 | X | − | 50 | ( | 400 | − | 10 | X | ) |
| = | 28000 | − | 300 | X | − | X | × | 10 | X | − | 50 | × | 400 | + | 50 | × | 10 | X |
| = | 28000 | − | 300 | X | − | X | × | 10 | X | − | 20000 | + | 500 | X |
| = | 8000 | + | 200 | X | − | X | × | 10 | X |
| 8000 | + | 200 | X | − | X | × | 10 | X | = | 9000 |