| 1 | ÷ | ( | 1 | ÷ | 750 | + | 1 | ÷ | x | ) | = | 400 |
| Multiply both sides of the equation by: | ( | 1 | ÷ | 750 | + | 1 | ÷ | x | ) |
| 1 | = | 400 | ( | 1 | ÷ | 750 | + | 1 | ÷ | x | ) |
| 1 | = | 400 | × | 1 | ÷ | 750 | + | 400 | × | 1 | ÷ | x |
| 1 | = | 8 15 | + | 400 | ÷ | x |
| Multiply both sides of the equation by: | x |
| 1 | x | = | 8 15 | x | + | 400 |
| 1 | x | − | 8 15 | x | = | 400 |
7 15 | x | = | 400 |
| x | = | 400 | ÷ | 7 15 |
| = | 400 | × | 15 7 |
| x | = | 6000 7 |
| x | = | 857.142857 |