| 4 | ( | 3 | z | + | 35 | − | z | ) | = | 2 | ( | 4 | z | + | 70 | − | 2 | z | ) |
| Left side of the equation = | 4 | × | 3 | z | + | 4 | × | 35 | − | 4 | z |
| = | 12 | z | + | 140 | − | 4 | z |
| = | 8 | z | + | 140 |
| 8 | z | + | 140 | = | 2 | ( | 4 | z | + | 70 | − | 2 | z | ) |
| Right side of the equation = | 2 | × | 4 | z | + | 2 | × | 70 | − | 2 | × | 2 | z |
| = | 8 | z | + | 140 | − | 4 | z |
| = | 4 | z | + | 140 |
| 8 | z | + | 140 | = | 4 | z | + | 140 |
| 8 | z | − | 4 | z | = | 140 | − | 140 |
| 4 | z | = | 140 | − | 140 |
| 4 | z | = | 0 |
| z | = | 0 | ÷ | 4 |
| = | 0 | × | 1 4 |
| z | = | 0 |