| ( | 15 | − | x | ) | ÷ | ( | 15 | − | 28 | ) | = | ( | 1800 | − | 3000 | ) | ÷ | ( | 1800 | − | 5700 | ) |
| Multiply both sides of the equation by: | ( | 15 | − | 28 | ) | , | ( | 1800 | − | 5700 | ) |
| ( | 15 | − | x | ) | ( | 1800 | − | 5700 | ) | = | ( | 1800 | − | 3000 | ) | ( | 15 | − | 28 | ) |
| 15 | ( | 1800 | − | 5700 | ) | − | x | ( | 1800 | − | 5700 | ) | = | ( | 1800 | − | 3000 | ) | ( | 15 | − | 28 | ) |
| 15 | ( | 1800 | − | 5700 | ) | − | x | ( | 1800 | − | 5700 | ) | = | 1800 | ( | 15 | − | 28 | ) | − | 3000 | ( | 15 | − | 28 | ) |
| 15 | × | 1800 | − | 15 | × | 5700 | − | x | ( | 1800 | − | 5700 | ) | = | 1800 | ( | 15 | − | 28 | ) | − | 3000 | ( | 15 | − | 28 | ) |
| 15 | × | 1800 | − | 15 | × | 5700 | − | x | ( | 1800 | − | 5700 | ) | = | 1800 | × | 15 | − | 1800 | × | 28 | − | 3000 | ( | 15 | − | 28 | ) |
| 27000 | − | 85500 | − | x | ( | 1800 | − | 5700 | ) | = | 27000 | − | 50400 | − | 3000 | ( | 15 | − | 28 | ) |
| - | 58500 | − | x | ( | 1800 | − | 5700 | ) | = | - | 23400 | − | 3000 | ( | 15 | − | 28 | ) |
| - | 58500 | − | x | × | 1800 | + | x | × | 5700 | = | - | 23400 | − | 3000 | ( | 15 | − | 28 | ) |
| - | 58500 | − | x | × | 1800 | + | x | × | 5700 | = | - | 23400 | − | 3000 | × | 15 | + | 3000 | × | 28 |
| - | 58500 | − | x | × | 1800 | + | x | × | 5700 | = | - | 23400 | − | 45000 | + | 84000 |
| - | 58500 | + | 3900 | x | = | 15600 |
| 3900 | x | = | 15600 | + | 58500 |
| 3900 | x | = | 74100 |
| x | = | 74100 | ÷ | 3900 |
| = | 74100 | × | 1 3900 |
| = | 19 | × | 1 |
| x | = | 19 |