| ( | 8 5 | x | − | x | ) | x | × | 200 | + | ( | 13 10 | x | − | x | ) | x | × | 100 | + | ( | 7 10 | x | − | x | ) | x | × | 100 | = | 15000 |
| Left side of the equation = | 8 5 | x | x | × | 200 | − | x | x | × | 200 | + | ( | 13 10 | x | − | x | ) | x | × | 100 | + | ( | 7 10 | x | − | x | ) | x |
| = | 320 | x | x | − | x | x | × | 200 | + | ( | 13 10 | x | − | x | ) | x | × | 100 | + | ( | 7 10 | x | − | x | ) | x | × | 100 |
| = | 320 | x | x | − | x | x | × | 200 | + | 13 10 | x | x | × | 100 | − | x | x |
| = | 320 | x | x | − | x | x | × | 200 | + | 130 | x | x | − | x | x | × | 100 |
| = | 320 | x | x | − | x | x | × | 200 | + | 130 | x | x | − | x | x | × | 100 |
| = | 320 | x | x | − | x | x | × | 200 | + | 130 | x | x | − | x | x | × | 100 |
| 320 | x | x | − | x | x | × | 200 | + | 130 | x | x | − | x | x | × | 100 | = | 15000 |