| ( | 3 | z | + | 35 | − | z | ) | ÷ | 4 | = | ( | 4 | z | + | 70 | − | 2 | z | ) | ÷ | 2 |
| 方程左边 = | 3 | z | × | 1 4 | + | 35 | × | 1 4 | − | z | × | 1 4 |
| = | 3 4 | z | + | 35 4 | − | z | × | 1 4 |
| = | 1 2 | z | + | 35 4 |
1 2 | z | + | 35 4 | = | ( | 4 | z | + | 70 | − | 2 | z | ) | ÷ | 2 |
| 方程右边 = | 4 | z | × | 1 2 | + | 70 | × | 1 2 | − | 2 | z | × | 1 2 |
| = | 2 | z | + | 35 | − | 1 | z |
| = | 1 | z | + | 35 |
1 2 | z | + | 35 4 | = | 1 | z | + | 35 |
1 2 | z | − | 1 | z | = | 35 | − | 35 4 |
| - | 1 2 | z | = | 35 | − | 35 4 |
| - | 1 2 | z | = | 105 4 |
| - | 105 4 | = | 1 2 | z |
1 2 | z | = | - | 105 4 |
| z | = | - | 105 4 | ÷ | 1 2 |
| = | - | 105 4 | × | 2 |
| = | - | 105 2 | × | 1 |
| z | = | - | 105 2 |
| z | = | - 52.5 |