| 500 | ÷ | 10000 | × | X | + | 120 | = | 800 | ÷ | 10000 | × | X |
| Left side of the equation = | 1 20 | X | + | 120 |
1 20 | X | + | 120 | = | 800 | ÷ | 10000 | × | X |
| Right side of the equation = | 2 25 | X |
1 20 | X | + | 120 | = | 2 25 | X |
1 20 | X | − | 2 25 | X | = | - | 120 |
| - | 3 100 | X | = | - | 120 |
| 120 | = | 3 100 | X |
3 100 | X | = | 120 |
| X | = | 120 | ÷ | 3 100 |
| = | 120 | × | 100 3 |
| = | 40 | × | 100 |
| X | = | 4000 |