| 20 | i | × | 1 | + | 6 | i | × | 2 | − | 140 | = | 0 |
| Left side of the equation = | 20 | i | + | 12 | i | − | 140 |
| = | 32 | i | − | 140 |
| 32 | i | − | 140 | = | 0 |
| 32 | i | = | 0 | + | 140 |
| 32 | i | = | 140 |
| i | = | 140 | ÷ | 32 |
| = | 140 | × | 1 32 |
| = | 35 | × | 1 8 |
| i | = | 35 8 |
| i | = | 4.375 |
| - | 5 | i | × | 2 | + | 6 | i | × | 3 | − | 90 | = | 0 |
| Left side of the equation = | - | 10 | i | + | 18 | i | − | 90 |
| = | 8 | i | − | 90 |
| 8 | i | − | 90 | = | 0 |
| 8 | i | = | 0 | + | 90 |
| 8 | i | = | 90 |
| i | = | 90 | ÷ | 8 |
| = | 90 | × | 1 8 |
| = | 45 | × | 1 4 |
| i | = | 45 4 |
| i | = | 11.25 |