15 100 | = | ( | 3 | X | × | 100 | + | X | × | 300 | ) | ÷ | 400 |
| Right side of the equation = | 3 | X | × | 100 | × | 1 400 | + | X | × | 300 | × | 1 400 |
| = | 3 4 | X | + | X | × | 3 4 |
| = | 3 2 | X |
15 100 | = | 3 2 | X |
| - | 3 2 | X | = | - | 15 100 |
15 100 | = | 3 2 | X |
3 2 | X | = | 15 100 |
| X | = | 15 100 | ÷ | 3 2 |
| = | 15 100 | × | 2 3 |
| = | 5 50 | × | 1 |
| X | = | 5 50 |
| X | = | 1 10 |
| X | = | 0.1 |