| x | + | ( | 3 | x | + | 3 | ) | + | ( | ( | 3 | x | + | 3 | ) | × | 2 | ) | = | 63 |
| 方程左边 = | x | + | 3 | x | + | 3 | + | ( | ( | 3 | x | + | 3 | ) | × | 2 | ) |
| = | 4 | x | + | 3 | + | ( | ( | 3 | x | + | 3 | ) | × | 2 | ) |
| = | 4 | x | + | 3 | + | ( | 3 | x | + | 3 | ) | × | 2 |
| = | 4 | x | + | 3 | + | 3 | x | × | 2 | + | 3 | × | 2 |
| = | 4 | x | + | 3 | + | 6 | x | + | 6 |
| = | 10 | x | + | 9 |
| 10 | x | + | 9 | = | 63 |
| 10 | x | = | 63 | − | 9 |
| 10 | x | = | 54 |
| x | = | 54 | ÷ | 10 |
| = | 54 | × | 1 10 |
| = | 27 | × | 1 5 |
| x | = | 27 5 |
| x | = | 5.4 |