| y | = | 100 | + | 4 5 | ( | y | − | 100 | + | 50 | ) | + | 200 | + | 100 |
| Right side of the equation = | 400 | + | 4 5 | ( | y | − | 100 | + | 50 | ) |
| y | = | 400 | + | 4 5 | ( | y | − | 100 | + | 50 | ) |
| Right side of the equation = | 400 | + | 4 5 | y | − | 4 5 | × | 100 | + | 4 5 | × | 50 |
| = | 400 | + | 4 5 | y | − | 80 | + | 40 |
| = | 360 | + | 4 5 | y |
| y | = | 360 | + | 4 5 | y |
| y | − | 4 5 | y | = | 360 |
1 5 | y | = | 360 |
| y | = | 360 | ÷ | 1 5 |
| = | 360 | × | 5 |
| y | = | 1800 |