17 200 | W | + | 18 100 | ( | 1 | − | W | ) | = | 71 500 |
| Left side of the equation = | 17 200 | W | + | 18 100 | × | 1 | − | 18 100 | W |
| = | 17 200 | W | + | 9 50 | − | 18 100 | W |
| = | - | 19 200 | W | + | 9 50 |
| - | 19 200 | W | + | 9 50 | = | 71 500 |
| - | 19 200 | W | = | 71 500 | − | 9 50 |
| - | 19 200 | W | = | - | 19 500 |
19 500 | = | 19 200 | W |
19 200 | W | = | 19 500 |
| W | = | 19 500 | ÷ | 19 200 |
| = | 19 500 | × | 200 19 |
| = | 1 5 | × | 2 |
| W | = | 2 5 |
| W | = | 0.4 |