9 100 | = | A | × | 54 500 | + | ( | 1 | − | A | ) | × | 27 1000 |
| 方程右边 = | 54 500 | A | + | 1 | × | 27 1000 | − | A | × | 27 1000 |
| = | 54 500 | A | + | 27 1000 | − | A | × | 27 1000 |
| = | 81 1000 | A | + | 27 1000 |
9 100 | = | 81 1000 | A | + | 27 1000 |
| - | 81 1000 | A | = | 27 1000 | − | 9 100 |
| - | 81 1000 | A | = | - | 63 1000 |
63 1000 | = | 81 1000 | A |
81 1000 | A | = | 63 1000 |
| A | = | 63 1000 | ÷ | 81 1000 |
| = | 63 1000 | × | 1000 81 |
| = | 7 | × | 1 9 |
| A | = | 7 9 |
| A | = | 0.777778 |