| ( | 40 | × | 10 100 | + | x | ) | × | 90 100 | = | 40 | − | 40 | × | 10 100 |
| Left side of the equation = | 40 | × | 10 100 | × | 90 100 | + | x | × | 90 100 |
| = | 18 5 | + | x | × | 90 100 |
18 5 | + | 90 100 | x | = | 40 | − | 40 | × | 10 100 |
| Right side of the equation = | 40 | − | 4 |
| = | 36 |
18 5 | + | 90 100 | x | = | 36 |
90 100 | x | = | 36 | − | 18 5 |
90 100 | x | = | 162 5 |
| x | = | 162 5 | ÷ | 90 100 |
| = | 162 5 | × | 100 90 |
| = | 9 | × | 20 5 |
| x | = | 180 5 |
| x | = | 36 |