| 300 | ( | 10 | + | X | ) | = | 300 | ( | 5 | + | X | ) |
| Left side of the equation = | 300 | × | 10 | + | 300 | X |
| = | 3000 | + | 300 | X |
| 3000 | + | 300 | X | = | 300 | ( | 5 | + | X | ) |
| Right side of the equation = | 300 | × | 5 | + | 300 | X |
| = | 1500 | + | 300 | X |
| 3000 | + | 300 | X | = | 1500 | + | 300 | X |
| 300 | X | − | 300 | X | = | 1500 | − | 3000 |
| 0 | X | = | 1500 | − | 3000 |
| 0 | X | = | - | 1500 |