| 2 | x | + | 40 | + | 20 | + | 20 | + | ( | 2 | x | + | 40 | + | 20 | + | 20 | ) | × | 3 20 | = | 129 |
| Left side of the equation = | 2 | x | + | 80 | + | ( | 2 | x | + | 40 | + | 20 | + | 20 | ) | × | 3 20 |
| 2 | x | + | 80 | + | ( | 2 | x | + | 40 | + | 20 | + | 20 | ) | × | 3 20 | = | 129 |
| Left side of the equation = | 2 | x | + | 80 | + | 2 | x | × | 3 20 | + | 40 | × | 3 20 | + | 20 | × | 3 20 | + | 20 | × | 3 20 |
| = | 2 | x | + | 80 | + | 3 10 | x | + | 6 | + | 3 | + | 3 |
| = | 23 10 | x | + | 92 |
23 10 | x | + | 92 | = | 129 |
23 10 | x | = | 129 | − | 92 |
23 10 | x | = | 37 |
| x | = | 37 | ÷ | 23 10 |
| = | 37 | × | 10 23 |
| x | = | 370 23 |
| x | = | 16.086957 |