| 5 | ( | 15 | + | x | ) | = | 3 | ( | 35 | + | x | ) |
| Left side of the equation = | 5 | × | 15 | + | 5 | x |
| = | 75 | + | 5 | x |
| 75 | + | 5 | x | = | 3 | ( | 35 | + | x | ) |
| Right side of the equation = | 3 | × | 35 | + | 3 | x |
| = | 105 | + | 3 | x |
| 75 | + | 5 | x | = | 105 | + | 3 | x |
| 5 | x | − | 3 | x | = | 105 | − | 75 |
| 2 | x | = | 105 | − | 75 |
| 2 | x | = | 30 |
| x | = | 30 | ÷ | 2 |
| = | 30 | × | 1 2 |
| = | 15 | × | 1 |
| x | = | 15 |