| 7 | X | + | 13 | = | 5 | X | − | 10 |
| 7 | X | − | 5 | X | = | - | 10 | − | 13 |
| 2 | X | = | - | 10 | − | 13 |
| 2 | X | = | - | 23 |
| X | = | - | 23 | ÷ | 2 |
| = | - | 23 | × | 1 2 |
| X | = | - | 23 2 |
| X | = | - 11.5 |
| 8 | X | + | 4 | = | 5 | + | 3 | X |
| 8 | X | − | 3 | X | = | 5 | − | 4 |
| 5 | X | = | 5 | − | 4 |
| 5 | X | = | 1 |
| X | = | 1 | ÷ | 5 |
| = | 1 | × | 1 5 |
| X | = | 1 5 |
| X | = | 0.2 |
| 5 | X | − | 10 | = | 4 | X | + | 10 |
| 5 | X | − | 4 | X | = | 10 | + | 10 |
| X | = | 10 | + | 10 |
| X | = | 10 | + | 10 |
| X | = | 20 |
| 6 | X | + | 40 | = | 4 | X | + | 80 |
| 6 | X | − | 4 | X | = | 80 | − | 40 |
| 2 | X | = | 80 | − | 40 |
| 2 | X | = | 40 |
| X | = | 40 | ÷ | 2 |
| = | 40 | × | 1 2 |
| = | 20 | × | 1 |
| X | = | 20 |
| 8 | X | + | 4 | = | 2 | X | + | 20 |
| 8 | X | − | 2 | X | = | 20 | − | 4 |
| 6 | X | = | 20 | − | 4 |
| 6 | X | = | 16 |
| X | = | 16 | ÷ | 6 |
| = | 16 | × | 1 6 |
| = | 8 | × | 1 3 |
| X | = | 8 3 |
| X | = | 2.666667 |