| ( | x | − | 20 | ) | × | 10 | × | 9 10 | = | x | ( | 5 | × | 3 4 | + | 5 | × | 13 20 | ) |
| Left side of the equation = | ( | x | − | 20 | ) | × | 9 |
| ( | x | − | 20 | ) | × | 9 | = | x | ( | 5 | × | 3 4 | + | 5 | × | 13 20 | ) |
| Left side of the equation = | x | × | 9 | − | 20 | × | 9 |
| = | x | × | 9 | − | 180 |
| 9 | x | − | 180 | = | x | ( | 5 | × | 3 4 | + | 5 | × | 13 20 | ) |
| Right side of the equation = | x | × | 5 | × | 3 4 | + | x | × | 5 | × | 13 20 |
| = | x | × | 15 4 | + | x | × | 13 4 |
| = | 7 | x |
| 9 | x | − | 180 | = | 7 | x |
| 9 | x | − | 7 | x | = | 180 |
| 2 | x | = | 180 |
| x | = | 180 | ÷ | 2 |
| = | 180 | × | 1 2 |
| = | 90 | × | 1 |
| x | = | 90 |