| 36 | c | × | 2 | − | 4 | × | 18 | ( | c | × | 2 | − | 144 | ) | = | 0 |
| 方程左边 = | 72 | c | − | 72 | ( | c | × | 2 | − | 144 | ) |
| 72 | c | − | 72 | ( | c | × | 2 | − | 144 | ) | = | 0 |
| 方程左边 = | 72 | c | − | 72 | c | × | 2 | + | 72 | × | 144 |
| = | 72 | c | − | 144 | c | + | 10368 |
| = | - | 72 | c | + | 10368 |
| - | 72 | c | + | 10368 | = | 0 |
| - | 72 | c | = | 0 | − | 10368 |
| - | 72 | c | = | - | 10368 |
| 10368 | = | 72 | c |
| 72 | c | = | 10368 |
| c | = | 10368 | ÷ | 72 |
| = | 10368 | × | 1 72 |
| = | 144 | × | 1 |
| c | = | 144 |