| ( | 7 | x | + | 40 | ) | ÷ | ( | 4 | x | + | 40 | ) | = | 8 | ÷ | 5 |
| Multiply both sides of the equation by: | ( | 4 | x | + | 40 | ) |
| ( | 7 | x | + | 40 | ) | = | 8 | ÷ | 5 | × | ( | 4 | x | + | 40 | ) |
| 7 | x | + | 40 | = | 8 | ÷ | 5 | × | ( | 4 | x | + | 40 | ) |
| 7 | x | + | 40 | = | 8 | ÷ | 5 | × | 4 | x | + | 8 | ÷ | 5 | × | 40 |
| 7 | x | + | 40 | = | 32 5 | x | + | 64 |
| 7 | x | − | 32 5 | x | = | 64 | − | 40 |
3 5 | x | = | 64 | − | 40 |
3 5 | x | = | 24 |
| x | = | 24 | ÷ | 3 5 |
| = | 24 | × | 5 3 |
| = | 8 | × | 5 |
| x | = | 40 |