| ( | a | − | 360 | ) | ( | 1 | − | 1 4 | ) | ÷ | 3800 | = | ( | a | − | 660 | ) | ( | 1 | − | 1 4 | ) | ÷ | 2800 |
| Left side of the equation = | a | ( | 1 | − | 1 4 | ) | × | 1 3800 | − | 360 | ( | 1 | − | 1 4 | ) | × | 1 3800 |
| = | a | ( | 1 | − | 1 4 | ) | × | 1 3800 | − | 9 95 | ( | 1 | − | 1 4 | ) |
| = | a | × | 1 | × | 1 3800 | − | a | × | 1 4 | × | 1 3800 | − | 9 95 | ( | 1 | − | 1 4 | ) |
| = | a | × | 1 3800 | − | a | × | 1 15200 | − | 9 95 | ( | 1 | − | 1 4 | ) |
| = | 3 15200 | a | − | 9 95 | ( | 1 | − | 1 4 | ) |
| = | 3 15200 | a | − | 9 95 | × | 1 | + | 9 95 | × | 1 4 |
| = | 3 15200 | a | − | 9 95 | + | 9 380 |
| = | 3 15200 | a | − | 27 380 |
3 15200 | a | − | 27 380 | = | ( | a | − | 660 | ) | ( | 1 | − | 1 4 | ) | ÷ | 2800 |
| Right side of the equation = | a | ( | 1 | − | 1 4 | ) | × | 1 2800 | − | 660 | ( | 1 | − | 1 4 | ) | × | 1 2800 |
| = | a | ( | 1 | − | 1 4 | ) | × | 1 2800 | − | 33 140 | ( | 1 | − | 1 4 | ) |
| = | a | × | 1 | × | 1 2800 | − | a | × | 1 4 | × | 1 2800 | − | 33 140 | ( | 1 | − | 1 4 | ) |
| = | a | × | 1 2800 | − | a | × | 1 11200 | − | 33 140 | ( | 1 | − | 1 4 | ) |
| = | 3 11200 | a | − | 33 140 | ( | 1 | − | 1 4 | ) |
| = | 3 11200 | a | − | 33 140 | × | 1 | + | 33 140 | × | 1 4 |
| = | 3 11200 | a | − | 33 140 | + | 33 560 |
| = | 3 11200 | a | − | 99 560 |
3 15200 | a | − | 27 380 | = | 3 11200 | a | − | 99 560 |
3 15200 | a | − | 3 11200 | a | = | - | 99 560 | + | 27 380 |
| - | 3 42560 | a | = | - | 99 560 | + | 27 380 |
| - | 3 42560 | a | = | - | 225 2128 |
225 2128 | = | 3 42560 | a |
3 42560 | a | = | 225 2128 |
| a | = | 225 2128 | ÷ | 3 42560 |
| = | 225 2128 | × | 42560 3 |
| = | 75 | × | 20 |
| a | = | 1500 |