| ( | 8690 | + | X | ) | × | 13 400 | = | 4 | X |
| Left side of the equation = | 8690 | × | 13 400 | + | X | × | 13 400 |
| = | 11297 40 | + | X | × | 13 400 |
11297 40 | + | 13 400 | X | = | 4 | X |
13 400 | X | − | 4 | X | = | - | 11297 40 |
| - | 1587 400 | X | = | - | 11297 40 |
11297 40 | = | 1587 400 | X |
1587 400 | X | = | 11297 40 |
| X | = | 11297 40 | ÷ | 1587 400 |
| = | 11297 40 | × | 400 1587 |
| = | 11297 | × | 10 1587 |
| X | = | 112970 1587 |
| X | = | 71.184625 |