| ( | 3 10 | − | X | ) | ( | 500 | + | 3000 | X | ) | = | 160 |
| Left side of the equation = | 3 10 | ( | 500 | + | 3000 | X | ) | − | X | ( | 500 | + | 3000 | X | ) |
| = | 3 10 | × | 500 | + | 3 10 | × | 3000 | X | − | X | ( | 500 | + | 3000 | X | ) |
| = | 150 | + | 900 | X | − | X | ( | 500 | + | 3000 | X | ) |
| = | 150 | + | 900 | X | − | X | × | 500 | − | X | × | 3000 | X |
| = | 150 | + | 400 | X | − | X | × | 3000 | X |
| 150 | + | 400 | X | − | X | × | 3000 | X | = | 160 |
| X1= | 1 30 |
| X2= | 1 10 |