| ( | ( | 600 | + | X | ) | ÷ | 1000 | ) | × | 100 100 | = | 80 100 |
| Left side of the equation = | ( | 600 | + | X | ) | ÷ | 1000 | × | 100 100 |
| = | ( | 600 | + | X | ) | × | 1 1000 |
| = | 600 | × | 1 1000 | + | X | × | 1 1000 |
| = | 3 5 | + | X | × | 1 1000 |
3 5 | + | 1 1000 | X | = | 80 100 |
1 1000 | X | = | 80 100 | − | 3 5 |
1 1000 | X | = | 1 5 |
| X | = | 1 5 | ÷ | 1 1000 |
| = | 1 5 | × | 1000 |
| = | 1 | × | 200 |
| X | = | 200 |