| 58 | + | 88 | + | 20 | x | + | 40 | ( | x | + | 1 20 | ) | = | 160 |
| Left side of the equation = | 146 | + | 20 | x | + | 40 | ( | x | + | 1 20 | ) |
| 146 | + | 20 | x | + | 40 | ( | x | + | 1 20 | ) | = | 160 |
| Left side of the equation = | 146 | + | 20 | x | + | 40 | x | + | 40 | × | 1 20 |
| = | 146 | + | 20 | x | + | 40 | x | + | 2 |
| = | 148 | + | 60 | x |
| 148 | + | 60 | x | = | 160 |
| 60 | x | = | 160 | − | 148 |
| 60 | x | = | 12 |
| x | = | 12 | ÷ | 60 |
| = | 12 | × | 1 60 |
| = | 1 | × | 1 5 |
| x | = | 1 5 |
| x | = | 0.2 |