| ( | 6480 | + | 1600 | ) | ( | x | − | 1 | ) | + | 12960 | = | 270 | × | 160 | × | 5 | + | 180 | × | 160 | × | 7 |
| Left side of the equation = | 6480 | ( | x | − | 1 | ) | + | 1600 | ( | x | − | 1 | ) | + | 12960 |
| = | 6480 | x | − | 6480 | × | 1 | + | 1600 | ( | x | − | 1 | ) | + | 12960 |
| = | 6480 | x | − | 6480 | + | 1600 | ( | x | − | 1 | ) | + | 12960 |
| = | 6480 | x | + | 6480 | + | 1600 | ( | x | − | 1 | ) |
| = | 6480 | x | + | 6480 | + | 1600 | x | − | 1600 | × | 1 |
| = | 6480 | x | + | 6480 | + | 1600 | x | − | 1600 |
| = | 8080 | x | + | 4880 |
| 8080 | x | + | 4880 | = | 270 | × | 160 | × | 5 | + | 180 | × | 160 | × | 7 |
| Right side of the equation = | 216000 | + | 201600 |
| = | 417600 |
| 8080 | x | + | 4880 | = | 417600 |
| 8080 | x | = | 417600 | − | 4880 |
| 8080 | x | = | 412720 |
| x | = | 412720 | ÷ | 8080 |
| = | 412720 | × | 1 8080 |
| = | 5159 | × | 1 101 |
| x | = | 5159 101 |
| x | = | 51.079208 |