| ( | X | − | 4 | ) | × | 240 | = | ( | X | + | 2 | ) | × | 80 |
| Left side of the equation = | X | × | 240 | − | 4 | × | 240 |
| = | X | × | 240 | − | 960 |
| 240 | X | − | 960 | = | ( | X | + | 2 | ) | × | 80 |
| Right side of the equation = | X | × | 80 | + | 2 | × | 80 |
| = | X | × | 80 | + | 160 |
| 240 | X | − | 960 | = | 80 | X | + | 160 |
| 240 | X | − | 80 | X | = | 160 | + | 960 |
| 160 | X | = | 160 | + | 960 |
| 160 | X | = | 1120 |
| X | = | 1120 | ÷ | 160 |
| = | 1120 | × | 1 160 |
| = | 7 | × | 1 |
| X | = | 7 |