| ( | 3 | + | 4 | ) | × | 10 | + | ( | 3 | + | X | + | 4 | ) | × | 4 | = | 120 |
| Left side of the equation = | 3 | × | 10 | + | 4 | × | 10 | + | ( | 3 | + | X | + | 4 | ) | × | 4 |
| = | 30 | + | 40 | + | ( | 3 | + | X | + | 4 | ) | × | 4 |
| = | 70 | + | ( | 3 | + | X | + | 4 | ) | × | 4 |
| = | 70 | + | 3 | × | 4 | + | X | × | 4 | + | 4 | × | 4 |
| = | 70 | + | 12 | + | X | × | 4 | + | 16 |
| = | 98 | + | 4 | X |
| 98 | + | 4 | X | = | 120 |
| 4 | X | = | 120 | − | 98 |
| 4 | X | = | 22 |
| X | = | 22 | ÷ | 4 |
| = | 22 | × | 1 4 |
| = | 11 | × | 1 2 |
| X | = | 11 2 |
| X | = | 5.5 |