69 20 | × | 320 | + | 21 5 | ( | x | − | 320 | ) | + | 69 20 | × | 320 | + | 21 5 | ( | 80 | ) | + | 26 5 | ( | 800 | − | x | − | 400 | ) | = | 2995 |
| Left side of the equation = | 1104 | + | 21 5 | ( | x | − | 320 | ) | + | 1104 | + | 21 5 | ( | 80 | ) | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| = | 2208 | + | 21 5 | ( | x | − | 320 | ) | + | 21 5 | ( | 80 | ) | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| 2208 | + | 21 5 | ( | x | − | 320 | ) | + | 21 5 | ( | 80 | ) | + | 26 5 | ( | 800 | − | x | − | 400 | ) | = | 2995 |
| Left side of the equation = | 2208 | + | 21 5 | x | − | 21 5 | × | 320 | + | 21 5 | ( | 80 | ) | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| = | 2208 | + | 21 5 | x | − | 1344 | + | 21 5 | ( | 80 | ) | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| = | 864 | + | 21 5 | x | + | 21 5 | ( | 80 | ) | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| = | 864 | + | 21 5 | x | + | 21 5 | × | 80 | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| = | 864 | + | 21 5 | x | + | 336 | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| = | 1200 | + | 21 5 | x | + | 26 5 | ( | 800 | − | x | − | 400 | ) |
| = | 1200 | + | 21 5 | x | + | 26 5 | × | 800 | − | 26 5 | x | − | 26 5 | × | 400 |
| = | 1200 | + | 21 5 | x | + | 4160 | − | 26 5 | x | − | 2080 |
| = | 3280 | − | 1 | x |
| 3280 | − | 1 | x | = | 2995 |
| - | 1 | x | = | 2995 | − | 3280 |
| - | x | = | 2995 | − | 3280 |
| - | x | = | - | 285 |
| 285 | = | x |
| x | = | 285 |