| 90 | × | 600 | ( | 1 | − | a | ) | + | 120 | × | 180 | ( | 1 | − | 9 | ÷ | 5 | × | a | ) | = | 62400 |
| Left side of the equation = | 54000 | ( | 1 | − | a | ) | + | 21600 | ( | 1 | − | 9 | ÷ | 5 | × | a | ) |
| 54000 | ( | 1 | − | a | ) | + | 21600 | ( | 1 | − | 9 | ÷ | 5 | × | a | ) | = | 62400 |
| Left side of the equation = | 54000 | × | 1 | − | 54000 | a | + | 21600 | ( | 1 | − | 9 | ÷ | 5 | × | a | ) |
| = | 54000 | − | 54000 | a | + | 21600 | ( | 1 | − | 9 | ÷ | 5 | × | a | ) |
| = | 54000 | − | 54000 | a | + | 21600 | × | 1 | − | 21600 | × | 9 | ÷ | 5 | × | a |
| = | 54000 | − | 54000 | a | + | 21600 | − | 38880 | a |
| = | 75600 | − | 92880 | a |
| 75600 | − | 92880 | a | = | 62400 |
| - | 92880 | a | = | 62400 | − | 75600 |
| - | 92880 | a | = | - | 13200 |
| 13200 | = | 92880 | a |
| 92880 | a | = | 13200 |
| a | = | 13200 | ÷ | 92880 |
| = | 13200 | × | 1 92880 |
| = | 55 | × | 1 387 |
| a | = | 55 387 |
| a | = | 0.142119 |