| ( | ( | 220 | + | 220 | ) | × | 42 | − | x | ) | × | 9 10 | + | 18 | × | 42 | = | 80631 5 |
| Left side of the equation = | ( | ( | 220 | + | 220 | ) | × | 42 | − | x | ) | × | 9 10 | + | 756 |
| ( | ( | 220 | + | 220 | ) | × | 42 | − | x | ) | × | 9 10 | + | 756 | = | 80631 5 |
| Left side of the equation = | ( | 220 | + | 220 | ) | × | 42 | × | 9 10 | − | x | × | 9 10 | + | 756 |
| = | ( | 220 | + | 220 | ) | × | 189 5 | − | x | × | 9 10 | + | 756 |
| = | 220 | × | 189 5 | + | 220 | × | 189 5 | − | 9 10 | x | + | 756 |
| = | 8316 | + | 8316 | − | 9 10 | x | + | 756 |
| = | 17388 | − | 9 10 | x |
| 17388 | − | 9 10 | x | = | 80631 5 |
| - | 9 10 | x | = | 80631 5 | − | 17388 |
| - | 9 10 | x | = | - | 6309 5 |
6309 5 | = | 9 10 | x |
9 10 | x | = | 6309 5 |
| x | = | 6309 5 | ÷ | 9 10 |
| = | 6309 5 | × | 10 9 |
| = | 701 | × | 2 |
| x | = | 1402 |