| 50 | × | 9 10 | + | ( | x | − | 50 | ) | × | 4 5 | = | 177 |
| Left side of the equation = | 45 | + | ( | x | − | 50 | ) | × | 4 5 |
| 45 | + | ( | x | − | 50 | ) | × | 4 5 | = | 177 |
| Left side of the equation = | 45 | + | x | × | 4 5 | − | 50 | × | 4 5 |
| = | 45 | + | x | × | 4 5 | − | 40 |
| = | 5 | + | 4 5 | x |
| 5 | + | 4 5 | x | = | 177 |
4 5 | x | = | 177 | − | 5 |
4 5 | x | = | 172 |
| x | = | 172 | ÷ | 4 5 |
| = | 172 | × | 5 4 |
| = | 43 | × | 5 |
| x | = | 215 |