| ( | 15 | + | 2 | x | ) | ( | 20 | + | 2 | x | ) | = | 246 | + | 20 | × | 15 |
| Left side of the equation = | 15 | ( | 20 | + | 2 | x | ) | + | 2 | x | ( | 20 | + | 2 | x | ) |
| = | 15 | × | 20 | + | 15 | × | 2 | x | + | 2 | x | ( | 20 | + | 2 | x | ) |
| = | 300 | + | 30 | x | + | 2 | x | ( | 20 | + | 2 | x | ) |
| = | 300 | + | 30 | x | + | 2 | x | × | 20 | + | 2 | x | × | 2 | x |
| = | 300 | + | 30 | x | + | 40 | x | + | 4 | x | x |
| = | 300 | + | 70 | x | + | 4 | x | x |
| 300 | + | 70 | x | + | 4 | x | x | = | 246 | + | 20 | × | 15 |
| Right side of the equation = | 246 | + | 300 |
| = | 546 |
| 300 | + | 70 | x | + | 4 | x | x | = | 546 |
| x1= | - | 41 2 |
| x2=3 |