| 6 | x | × | 7 | = | ( | 6 | x | + | 7 | x | ) | × | 3 | + | 45 |
| Left side of the equation = | 42 | x |
| 42 | x | = | ( | 6 | x | + | 7 | x | ) | × | 3 | + | 45 |
| Right side of the equation = | 6 | x | × | 3 | + | 7 | x | × | 3 | + | 45 |
| = | 18 | x | + | 21 | x | + | 45 |
| = | 39 | x | + | 45 |
| 42 | x | = | 39 | x | + | 45 |
| 42 | x | − | 39 | x | = | 45 |
| 3 | x | = | 45 |
| x | = | 45 | ÷ | 3 |
| = | 45 | × | 1 3 |
| = | 15 | × | 1 |
| x | = | 15 |