12 5 | × | 4000 | ( | 1 | + | x | ) | + | 12 5 | × | 5000 | ( | 1 | + | x | ) | ( | 1 | + | 2 | x | ) | = | 21600 | ( | 1 | + | 20 | x | ÷ | 9 | ) |
| Left side of the equation = | 9600 | ( | 1 | + | x | ) | + | 12000 | ( | 1 | + | x | ) | ( | 1 | + | 2 | x | ) |
| 9600 | ( | 1 | + | x | ) | + | 12000 | ( | 1 | + | x | ) | ( | 1 | + | 2 | x | ) | = | 21600 | ( | 1 | + | 20 | x | ÷ | 9 | ) |
| Left side of the equation = | 9600 | × | 1 | + | 9600 | x | + | 12000 | ( | 1 | + | x | ) | ( | 1 | + | 2 | x | ) |
| = | 9600 | + | 9600 | x | + | 12000 | ( | 1 | + | x | ) | ( | 1 | + | 2 | x | ) |
| = | 9600 | + | 9600 | x | + | 12000 | × | 1 | ( | 1 | + | 2 | x | ) | + | 12000 | x | ( | 1 | + | 2 | x | ) |
| = | 9600 | + | 9600 | x | + | 12000 | ( | 1 | + | 2 | x | ) | + | 12000 | x | ( | 1 | + | 2 | x | ) |
| = | 9600 | + | 9600 | x | + | 12000 | × | 1 | + | 12000 | × | 2 | x | + | 12000 | x | ( | 1 | + | 2 | x | ) |
| = | 9600 | + | 9600 | x | + | 12000 | + | 24000 | x | + | 12000 | x | ( | 1 | + | 2 | x | ) |
| = | 21600 | + | 33600 | x | + | 12000 | x | ( | 1 | + | 2 | x | ) |
| = | 21600 | + | 33600 | x | + | 12000 | x | × | 1 | + | 12000 | x | × | 2 | x |
| = | 21600 | + | 33600 | x | + | 12000 | x | + | 24000 | x | x |
| = | 21600 | + | 45600 | x | + | 24000 | x | x |
| 21600 | + | 45600 | x | + | 24000 | x | x | = | 21600 | ( | 1 | + | 20 | x | ÷ | 9 | ) |
| Right side of the equation = | 21600 | × | 1 | + | 21600 | × | 20 | x | ÷ | 9 |
| = | 21600 | + | 48000 | x |
| 21600 | + | 45600 | x | + | 24000 | x | x | = | 21600 | + | 48000 | x |
| x2= | 1 10 |