| a | × | 18 100 | + | ( | 1 | − | a | ) | × | 13 100 | = | 16 100 |
| Left side of the equation = | 18 100 | a | + | 1 | × | 13 100 | − | a | × | 13 100 |
| = | 18 100 | a | + | 13 100 | − | a | × | 13 100 |
| = | 1 20 | a | + | 13 100 |
1 20 | a | + | 13 100 | = | 16 100 |
1 20 | a | = | 16 100 | − | 13 100 |
1 20 | a | = | 3 100 |
| a | = | 3 100 | ÷ | 1 20 |
| = | 3 100 | × | 20 |
| = | 3 5 | × | 1 |
| a | = | 3 5 |
| a | = | 0.6 |