9 10 | ( | y | + | 10 | ) | ( | 600 | − | 20 | y | ) | − | 3 2 | ( | 600 | − | 20 | y | ) | − | 300 | = | 6000 |
| Left side of the equation = | 9 10 | y | ( | 600 | − | 20 | y | ) | + | 9 10 | × | 10 | ( | 600 | − | 20 | y | ) | − | 3 2 | ( | 600 | − | 20 | y | ) | − | 300 |
| = | 9 10 | y | ( | 600 | − | 20 | y | ) | + | 9 | ( | 600 | − | 20 | y | ) | − | 3 2 | ( | 600 | − | 20 | y | ) | − | 300 |
| = | 9 10 | y | × | 600 | − | 9 10 | y | × | 20 | y | + | 9 | ( | 600 | − | 20 | y | ) | − | 3 2 | ( | 600 | − | 20 | y | ) | − | 300 |
| = | 540 | y | − | 18 | y | y | + | 9 | ( | 600 | − | 20 | y | ) | − | 3 2 | ( | 600 | − | 20 | y | ) | − | 300 |
| = | 540 | y | − | 18 | y | y | + | 9 | × | 600 | − | 9 | × | 20 | y | − | 3 2 | ( | 600 | − | 20 | y | ) |
| = | 540 | y | − | 18 | y | y | + | 5400 | − | 180 | y | − | 3 2 | ( | 600 | − | 20 | y | ) | − | 300 |
| = | 360 | y | − | 18 | y | y | + | 5100 | − | 3 2 | ( | 600 | − | 20 | y | ) |
| = | 360 | y | − | 18 | y | y | + | 5100 | − | 3 2 | × | 600 | + | 3 2 | × | 20 | y |
| = | 360 | y | − | 18 | y | y | + | 5100 | − | 900 | + | 30 | y |
| = | 390 | y | − | 18 | y | y | + | 4200 |
| 390 | y | − | 18 | y | y | + | 4200 | = | 6000 |
| y1= | 20 3 |
| y2=15 |