| ( | 400 | ( | 1 | + | x | ÷ | 100 | ) | − | 50 | ) | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | = | 378 |
| Left side of the equation = | 400 | ( | 1 | + | x | ÷ | 100 | ) | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 400 | × | 1 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | + | 400 | x | ÷ | 100 | × | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 400 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | + | 4 | x | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 400 | × | 1 | + | 400 | ( | x | + | 5 2 | ) | ÷ | 100 | + | 4 | x | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 400 | + | 4 | ( | x | + | 5 2 | ) | + | 4 | x | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 400 | + | 4 | x | + | 4 | × | 5 2 | + | 4 | x | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 400 | + | 4 | x | + | 10 | + | 4 | x | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 4 | x | + | 4 | x | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 4 | x | + | 4 | x | × | 1 | + | 4 | x | ( | x | + | 5 2 | ) | ÷ | 100 | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 4 | x | + | 4 | x | + | 1 25 | x | ( | x | + | 5 2 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 8 | x | + | 1 25 | x | ( | x | + | 5 2 | ) | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 8 | x | + | 1 25 | x | x | + | 1 25 | x | × | 5 2 | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 8 | x | + | 1 25 | x | x | + | 1 10 | x | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 81 10 | x | + | 1 25 | x | x | − | 50 | ( | 1 | + | ( | x | + | 5 2 | ) | ÷ | 100 | ) |
| = | 410 | + | 81 10 | x | + | 1 25 | x | x | − | 50 | × | 1 | − | 50 | ( | x | + | 5 2 | ) | ÷ | 100 |
| = | 410 | + | 81 10 | x | + | 1 25 | x | x | − | 50 | − | 1 2 | ( | x | + | 5 2 | ) |
| = | 360 | + | 81 10 | x | + | 1 25 | x | x | − | 1 2 | ( | x | + | 5 2 | ) |
| = | 360 | + | 81 10 | x | + | 1 25 | x | x | − | 1 2 | x | − | 1 2 | × | 5 2 |
| = | 360 | + | 81 10 | x | + | 1 25 | x | x | − | 1 2 | x | − | 5 4 |
| = | 1435 4 | + | 38 5 | x | + | 1 25 | x | x |
1435 4 | + | 38 5 | x | + | 1 25 | x | x | = | 378 |
| x1= | - | 385 2 |
| x2= | 5 2 |