| ( | 400 | + | x | ) | ÷ | 45 | = | ( | 380 | + | x | ) | ÷ | 43 |
| Left side of the equation = | 400 | × | 1 45 | + | x | × | 1 45 |
| = | 80 9 | + | x | × | 1 45 |
80 9 | + | 1 45 | x | = | ( | 380 | + | x | ) | ÷ | 43 |
| Right side of the equation = | 380 | × | 1 43 | + | x | × | 1 43 |
| = | 380 43 | + | x | × | 1 43 |
80 9 | + | 1 45 | x | = | 380 43 | + | 1 43 | x |
1 45 | x | − | 1 43 | x | = | 380 43 | − | 80 9 |
| - | 2 1935 | x | = | 380 43 | − | 80 9 |
| - | 2 1935 | x | = | - | 20 387 |
20 387 | = | 2 1935 | x |
2 1935 | x | = | 20 387 |
| x | = | 20 387 | ÷ | 2 1935 |
| = | 20 387 | × | 1935 2 |
| = | 10 | × | 5 |
| x | = | 50 |