| ( | x | ÷ | 28 | ) | + | ( | 21 10 | − | x | ) | ÷ | 2 | = | 7 40 |
| Left side of the equation = | x | ÷ | 28 | + | ( | 21 10 | − | x | ) | × | 1 2 |
| = | 1 28 | x | + | 21 10 | × | 1 2 | − | x | × | 1 2 |
| = | 1 28 | x | + | 21 20 | − | x | × | 1 2 |
| = | - | 13 28 | x | + | 21 20 |
| - | 13 28 | x | + | 21 20 | = | 7 40 |
| - | 13 28 | x | = | 7 40 | − | 21 20 |
| - | 13 28 | x | = | - | 7 8 |
7 8 | = | 13 28 | x |
13 28 | x | = | 7 8 |
| x | = | 7 8 | ÷ | 13 28 |
| = | 7 8 | × | 28 13 |
| = | 7 2 | × | 7 13 |
| x | = | 49 26 |
| x | = | 1.884615 |