| 3 | ( | N | × | 129 | × | 1 5 | + | 400 | ) | = | N | × | 129 | × | 4 5 | − | 400 |
| Left side of the equation = | 3 | N | × | 129 | × | 1 5 | + | 3 | × | 400 |
| = | 387 5 | N | + | 1200 |
387 5 | N | + | 1200 | = | N | × | 129 | × | 4 5 | − | 400 |
| Right side of the equation = | N | × | 516 5 | − | 400 |
387 5 | N | + | 1200 | = | 516 5 | N | − | 400 |
387 5 | N | − | 516 5 | N | = | - | 400 | − | 1200 |
| - | 129 5 | N | = | - | 400 | − | 1200 |
| - | 129 5 | N | = | - | 1600 |
| 1600 | = | 129 5 | N |
129 5 | N | = | 1600 |
| N | = | 1600 | ÷ | 129 5 |
| = | 1600 | × | 5 129 |
| N | = | 8000 129 |
| N | = | 62.015504 |