| 500 | ( | 1 | + | x | ) | × | 2 | = | 720 |
| Left side of the equation = | 1000 | ( | 1 | + | x | ) |
| 1000 | ( | 1 | + | x | ) | = | 720 |
| Left side of the equation = | 1000 | × | 1 | + | 1000 | x |
| = | 1000 | + | 1000 | x |
| 1000 | + | 1000 | x | = | 720 |
| 1000 | x | = | 720 | − | 1000 |
| 1000 | x | = | - | 280 |
| x | = | - | 280 | ÷ | 1000 |
| = | - | 280 | × | 1 1000 |
| = | - | 7 | × | 1 25 |
| x | = | - | 7 25 |
| x | = | - 0.28 |