| 100 | × | 4 | x | + | 200 | x | = | ( | 100 | + | 200 | ) | × | 12 100 |
| Left side of the equation = | 400 | x | + | 200 | x |
| = | 600 | x |
| 600 | x | = | ( | 100 | + | 200 | ) | × | 12 100 |
| Right side of the equation = | 100 | × | 12 100 | + | 200 | × | 12 100 |
| = | 12 | + | 24 |
| = | 36 |
| 600 | x | = | 36 |
| x | = | 36 | ÷ | 600 |
| = | 36 | × | 1 600 |
| = | 3 | × | 1 50 |
| x | = | 3 50 |
| x | = | 0.06 |