| ( | 300 | − | x | ) | × | 3 | ÷ | 10 | = | ( | 400 | − | x | ) | × | 2 | ÷ | 10 |
| Left side of the equation = | ( | 300 | − | x | ) | × | 3 10 |
| ( | 300 | − | x | ) | × | 3 10 | = | ( | 400 | − | x | ) | × | 2 | ÷ | 10 |
| Left side of the equation = | 300 | × | 3 10 | − | x | × | 3 10 |
| = | 90 | − | x | × | 3 10 |
| 90 | − | 3 10 | x | = | ( | 400 | − | x | ) | × | 2 | ÷ | 10 |
| Right side of the equation = | ( | 400 | − | x | ) | × | 1 5 |
| 90 | − | 3 10 | x | = | ( | 400 | − | x | ) | × | 1 5 |
| Right side of the equation = | 400 | × | 1 5 | − | x | × | 1 5 |
| = | 80 | − | x | × | 1 5 |
| 90 | − | 3 10 | x | = | 80 | − | 1 5 | x |
| - | 3 10 | x | + | 1 5 | x | = | 80 | − | 90 |
| - | 1 10 | x | = | 80 | − | 90 |
| - | 1 10 | x | = | - | 10 |
| 10 | = | 1 10 | x |
1 10 | x | = | 10 |
| x | = | 10 | ÷ | 1 10 |
| = | 10 | × | 10 |
| x | = | 100 |