| x | − | 40 100 | x | − | 5 | − | ( | 40 100 | x | + | 5 | ) | × | 80 100 | = | 12 |
| Left side of the equation = | 3 5 | x | − | 5 | − | ( | 40 100 | x | + | 5 | ) | × | 80 100 |
3 5 | x | − | 5 | − | ( | 40 100 | x | + | 5 | ) | × | 80 100 | = | 12 |
| Left side of the equation = | 3 5 | x | − | 5 | − | 40 100 | x | × | 80 100 | − | 5 | × | 80 100 |
| = | 3 5 | x | − | 5 | − | 8 25 | x | − | 4 |
| = | 7 25 | x | − | 9 |
7 25 | x | − | 9 | = | 12 |
7 25 | x | = | 12 | + | 9 |
7 25 | x | = | 21 |
| x | = | 21 | ÷ | 7 25 |
| = | 21 | × | 25 7 |
| = | 3 | × | 25 |
| x | = | 75 |