| ( | - | 2 | x | + | 152 | − | 18 | ) | ( | 20 | + | 4 | x | ) | = | 870 |
| Left side of the equation = | - | 2 | x | ( | 20 | + | 4 | x | ) | + | 152 | ( | 20 | + | 4 | x | ) | − | 18 | ( | 20 | + | 4 | x | ) |
| = | - | 2 | x | × | 20 | − | 2 | x | × | 4 | x | + | 152 | ( | 20 | + | 4 | x | ) | − | 18 | ( | 20 | + | 4 | x | ) |
| = | - | 40 | x | − | 8 | x | x | + | 152 | ( | 20 | + | 4 | x | ) | − | 18 | ( | 20 | + | 4 | x | ) |
| = | - | 40 | x | − | 8 | x | x | + | 152 | × | 20 | + | 152 | × | 4 | x | − | 18 | ( | 20 | + | 4 | x | ) |
| = | - | 40 | x | − | 8 | x | x | + | 3040 | + | 608 | x | − | 18 | ( | 20 | + | 4 | x | ) |
| = | 568 | x | − | 8 | x | x | + | 3040 | − | 18 | ( | 20 | + | 4 | x | ) |
| = | 568 | x | − | 8 | x | x | + | 3040 | − | 18 | × | 20 | − | 18 | × | 4 | x |
| = | 568 | x | − | 8 | x | x | + | 3040 | − | 360 | − | 72 | x |
| = | 496 | x | − | 8 | x | x | + | 2680 |
| 496 | x | − | 8 | x | x | + | 2680 | = | 870 |