| ( | 90 | − | 46 | − | x | ) | ( | 20 | + | 5 | x | ) | = | 2400 |
| Left side of the equation = | 90 | ( | 20 | + | 5 | x | ) | − | 46 | ( | 20 | + | 5 | x | ) | − | x | ( | 20 | + | 5 | x | ) |
| = | 90 | × | 20 | + | 90 | × | 5 | x | − | 46 | ( | 20 | + | 5 | x | ) | − | x | ( | 20 | + | 5 | x | ) |
| = | 1800 | + | 450 | x | − | 46 | ( | 20 | + | 5 | x | ) | − | x | ( | 20 | + | 5 | x | ) |
| = | 1800 | + | 450 | x | − | 46 | × | 20 | − | 46 | × | 5 | x | − | x | ( | 20 | + | 5 | x | ) |
| = | 1800 | + | 450 | x | − | 920 | − | 230 | x | − | x | ( | 20 | + | 5 | x | ) |
| = | 880 | + | 220 | x | − | x | ( | 20 | + | 5 | x | ) |
| = | 880 | + | 220 | x | − | x | × | 20 | − | x | × | 5 | x |
| = | 880 | + | 200 | x | − | x | × | 5 | x |
| 880 | + | 200 | x | − | x | × | 5 | x | = | 2400 |