| 5 | ( | 5 | a | + | 5 | + | 5 | a | + | 10 | ) | ÷ | 2 | + | ( | 5 | a | + | 5 | ) | ( | a | + | 1 | ) | ÷ | 2 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | ÷ | 2 | = | 30 |
| Left side of the equation = | 5 2 | ( | 5 | a | + | 5 | + | 5 | a | + | 10 | ) | + | ( | 5 | a | + | 5 | ) | ( | a | + | 1 | ) | × | 1 2 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 |
5 2 | ( | 5 | a | + | 5 | + | 5 | a | + | 10 | ) | + | ( | 5 | a | + | 5 | ) | ( | a | + | 1 | ) | × | 1 2 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 | = | 30 |
| Left side of the equation = | 5 2 | × | 5 | a | + | 5 2 | × | 5 | + | 5 2 | × | 5 | a | + | 5 2 | × | 10 | + | ( | 5 | a | + | 5 | ) | ( | a | + | 1 | ) |
| = | 25 2 | a | + | 25 2 | + | 25 2 | a | + | 25 | + | ( | 5 | a | + | 5 | ) | ( | a | + | 1 | ) | × | 1 2 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 25 | a | + | 75 2 | + | ( | 5 | a | + | 5 | ) | ( | a | + | 1 | ) | × | 1 2 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 25 | a | + | 75 2 | + | 5 | a | ( | a | + | 1 | ) | × | 1 2 | + | 5 | ( | a | + | 1 | ) | × | 1 2 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) |
| = | 25 | a | + | 75 2 | + | 5 2 | a | ( | a | + | 1 | ) | + | 5 2 | ( | a | + | 1 | ) | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 25 | a | + | 75 2 | + | 5 2 | a | a | + | 5 2 | a | × | 1 | + | 5 2 | ( | a | + | 1 | ) | + | ( | 4 | − | a | ) |
| = | 25 | a | + | 75 2 | + | 5 2 | a | a | + | 5 2 | a | + | 5 2 | ( | a | + | 1 | ) | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) |
| = | 55 2 | a | + | 75 2 | + | 5 2 | a | a | + | 5 2 | ( | a | + | 1 | ) | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 55 2 | a | + | 75 2 | + | 5 2 | a | a | + | 5 2 | a | + | 5 2 | × | 1 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) |
| = | 55 2 | a | + | 75 2 | + | 5 2 | a | a | + | 5 2 | a | + | 5 2 | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 30 | a | + | 40 | + | 5 2 | a | a | + | ( | 4 | − | a | ) | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 30 | a | + | 40 | + | 5 2 | a | a | + | 4 | ( | 5 | a | + | 10 | ) | × | 1 2 | − | a | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 30 | a | + | 40 | + | 5 2 | a | a | + | 2 | ( | 5 | a | + | 10 | ) | − | a | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 30 | a | + | 40 | + | 5 2 | a | a | + | 2 | × | 5 | a | + | 2 | × | 10 | − | a |
| = | 30 | a | + | 40 | + | 5 2 | a | a | + | 10 | a | + | 20 | − | a | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 40 | a | + | 60 | + | 5 2 | a | a | − | a | ( | 5 | a | + | 10 | ) | × | 1 2 |
| = | 40 | a | + | 60 | + | 5 2 | a | a | − | a | × | 5 | a | × | 1 2 | − | a | × | 10 |
| = | 40 | a | + | 60 | + | 5 2 | a | a | − | a | × | 5 2 | a | − | a | × | 5 |
| = | 35 | a | + | 60 | + | 5 2 | a | a | − | a | × | 5 2 | a |
| 35 | a | + | 60 | + | 5 2 | a | a | − | a | × | 5 2 | a | = | 30 |
| a= | - | 6 7 |