| ( | x | − | 500 | ) | × | 5 | + | ( | x | − | ( | x | − | 500 | ) | − | ( | x | − | 800 | ) | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 | − | 6 5 | x | = | 3100 |
| Left side of the equation = | x | × | 5 | − | 500 | × | 5 | + | ( | x | − | ( | x | − | 500 | ) | − | ( | x | − | 800 | ) | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 | − | 6 5 | x |
| = | x | × | 5 | − | 2500 | + | ( | x | − | ( | x | − | 500 | ) | − | ( | x | − | 800 | ) | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 | − | 6 5 | x |
| = | 19 5 | x | − | 2500 | + | ( | x | − | ( | x | − | 500 | ) | − | ( | x | − | 800 | ) | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 |
| = | 19 5 | x | − | 2500 | + | x | × | 4 | − | ( | x | − | 500 | ) | × | 4 | − | ( | x | − | 800 | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 |
| = | 39 5 | x | − | 2500 | − | ( | x | − | 500 | ) | × | 4 | − | ( | x | − | 800 | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 |
| = | 39 5 | x | − | 2500 | − | x | × | 4 | + | 500 | × | 4 | − | ( | x | − | 800 | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 |
| = | 39 5 | x | − | 2500 | − | x | × | 4 | + | 2000 | − | ( | x | − | 800 | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 |
| = | 19 5 | x | − | 500 | − | ( | x | − | 800 | ) | × | 4 | + | ( | x | − | 800 | ) | × | 3 |
| = | 19 5 | x | − | 500 | − | x | × | 4 | + | 800 | × | 4 | + | ( | x | − | 800 | ) | × | 3 |
| = | 19 5 | x | − | 500 | − | x | × | 4 | + | 3200 | + | ( | x | − | 800 | ) | × | 3 |
| = | - | 1 5 | x | + | 2700 | + | ( | x | − | 800 | ) | × | 3 |
| = | - | 1 5 | x | + | 2700 | + | x | × | 3 | − | 800 | × | 3 |
| = | - | 1 5 | x | + | 2700 | + | x | × | 3 | − | 2400 |
| = | 14 5 | x | + | 300 |
14 5 | x | + | 300 | = | 3100 |
14 5 | x | = | 3100 | − | 300 |
14 5 | x | = | 2800 |
| x | = | 2800 | ÷ | 14 5 |
| = | 2800 | × | 5 14 |
| = | 200 | × | 5 |
| x | = | 1000 |