| ( | x | + | 3 | ) | × | 20 | = | ( | 1 | + | ( | 3 | x | − | 10 | ) | ) | × | 20 |
| Left side of the equation = | x | × | 20 | + | 3 | × | 20 |
| = | x | × | 20 | + | 60 |
| 20 | x | + | 60 | = | ( | 1 | + | ( | 3 | x | − | 10 | ) | ) | × | 20 |
| Right side of the equation = | 1 | × | 20 | + | ( | 3 | x | − | 10 | ) | × | 20 |
| = | 20 | + | ( | 3 | x | − | 10 | ) | × | 20 |
| = | 20 | + | 3 | x | × | 20 | − | 10 | × | 20 |
| = | 20 | + | 60 | x | − | 200 |
| = | - | 180 | + | 60 | x |
| 20 | x | + | 60 | = | - | 180 | + | 60 | x |
| 20 | x | − | 60 | x | = | - | 180 | − | 60 |
| - | 40 | x | = | - | 180 | − | 60 |
| - | 40 | x | = | - | 240 |
| 240 | = | 40 | x |
| 40 | x | = | 240 |
| x | = | 240 | ÷ | 40 |
| = | 240 | × | 1 40 |
| = | 6 | × | 1 |
| x | = | 6 |