| ( | x | + | 12 | ) | × | 4 | ÷ | 5 | + | x | = | 42 |
| Left side of the equation = | ( | x | + | 12 | ) | × | 4 5 | + | x |
| ( | x | + | 12 | ) | × | 4 5 | + | x | = | 42 |
| Left side of the equation = | x | × | 4 5 | + | 12 | × | 4 5 | + | x |
| = | x | × | 4 5 | + | 48 5 | + | x |
| = | 9 5 | x | + | 48 5 |
9 5 | x | + | 48 5 | = | 42 |
9 5 | x | = | 42 | − | 48 5 |
9 5 | x | = | 162 5 |
| x | = | 162 5 | ÷ | 9 5 |
| = | 162 5 | × | 5 9 |
| = | 18 | × | 1 |
| x | = | 18 |