| 4000 | × | 3 20 | ( | x | + | 7 10 | ) | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 30000 | × | 7 10 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| Left side of the equation = | 600 | ( | x | + | 7 10 | ) | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 |
| 600 | ( | x | + | 7 10 | ) | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| Left side of the equation = | 600 | x | + | 600 | × | 7 10 | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 |
| = | 600 | x | + | 420 | + | 700 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 21000 |
| = | 2200 | x | + | 21420 | + | 700 | ( | 3 10 | − | x | ) |
| = | 2200 | x | + | 21420 | + | 700 | × | 3 10 | − | 700 | x |
| = | 2200 | x | + | 21420 | + | 210 | − | 700 | x |
| = | 1500 | x | + | 21630 |
| 1500 | x | + | 21630 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| Right side of the equation = | 16000 | × | 3 20 | x | + | 16000 | × | 3 20 | × | 7 10 | + | 16000 | × | 1 |
| = | 2400 | x | + | 1680 | + | 16000 |
| = | 2400 | x | + | 17680 |
| 1500 | x | + | 21630 | = | 2400 | x | + | 17680 |
| 1500 | x | − | 2400 | x | = | 17680 | − | 21630 |
| - | 900 | x | = | 17680 | − | 21630 |
| - | 900 | x | = | - | 3950 |
| 3950 | = | 900 | x |
| 900 | x | = | 3950 |
| x | = | 3950 | ÷ | 900 |
| = | 3950 | × | 1 900 |
| = | 79 | × | 1 18 |
| x | = | 79 18 |
| x | = | 4.388889 |