| 1600 | + | ( | y | − | 50 | ) | ( | 200 | + | 10 | ( | 80 | − | y | ) | ) | = | 9000 |
| Left side of the equation = | 1600 | + | y | ( | 200 | + | 10 | ( | 80 | − | y | ) | ) | − | 50 | ( | 200 | + | 10 | ( | 80 | − | y | ) | ) |
| = | 1600 | + | y | × | 200 | + | y | × | 10 | ( | 80 | − | y | ) | − | 50 | ( | 200 | + | 10 | ( | 80 | − | y | ) | ) |
| = | 1600 | + | 200 | y | + | y | × | 10 | × | 80 | − | y | × | 10 | y | − | 50 | ( | 200 | + | 10 | ( | 80 | − | y | ) | ) |
| = | 1600 | + | 200 | y | + | y | × | 800 | − | y | × | 10 | y | − | 50 | ( | 200 | + | 10 | ( | 80 | − | y | ) | ) |
| = | 1600 | + | 1000 | y | − | y | × | 10 | y | − | 50 | ( | 200 | + | 10 | ( | 80 | − | y | ) | ) |
| = | 1600 | + | 1000 | y | − | y | × | 10 | y | − | 50 | × | 200 | − | 50 | × | 10 | ( | 80 | − | y | ) |
| = | 1600 | + | 1000 | y | − | y | × | 10 | y | − | 10000 | − | 500 | ( | 80 | − | y | ) |
| = | - | 8400 | + | 1000 | y | − | y | × | 10 | y | − | 500 | ( | 80 | − | y | ) |
| = | - | 8400 | + | 1000 | y | − | y | × | 10 | y | − | 500 | × | 80 | + | 500 | y |
| = | - | 8400 | + | 1000 | y | − | y | × | 10 | y | − | 40000 | + | 500 | y |
| = | - | 48400 | + | 1500 | y | − | y | × | 10 | y |
| - | 48400 | + | 1500 | y | − | y | × | 10 | y | = | 9000 |