| x | − | 1 5 | − | 21 | − | ( | 1 5 | x | + | 21 | ) | = | 3 40 | x |
| Left side of the equation = | x | − | 106 5 | − | ( | 1 5 | x | + | 21 | ) |
| x | − | 106 5 | − | ( | 1 5 | x | + | 21 | ) | = | 3 40 | x |
| Left side of the equation = | x | − | 106 5 | − | 1 5 | x | − | 21 |
| = | 4 5 | x | − | 211 5 |
4 5 | x | − | 211 5 | = | 3 40 | x |
4 5 | x | − | 3 40 | x | = | 211 5 |
29 40 | x | = | 211 5 |
| x | = | 211 5 | ÷ | 29 40 |
| = | 211 5 | × | 40 29 |
| = | 211 | × | 8 29 |
| x | = | 1688 29 |
| x | = | 58.206897 |