| ( | 420000000 | − | 250000 | x | ) | ( | 200000000 | − | 200000 | x | ) | − | 40000000000000000 | = | 0 |
| Left side of the equation = | 420000000 | ( | 200000000 | − | 200000 | x | ) | − | 250000 | x | ( | 200000000 | − | 200000 | x | ) | − | 40000000000000000 |
| = | 420000000 | × | 200000000 | − | 420000000 | × | 200000 | x | − | 250000 | x | ( | 200000000 | − | 200000 | x | ) | − | 40000000000000000 |