| x | ÷ | 5 | = | ( | 100 | × | 100 | ÷ | ( | 100 | + | 80 | ) | ) |
| x | ÷ | 5 | = | 100 | × | 100 | ÷ | ( | 100 | + | 80 | ) |
| x | × | 1 5 | = | 10000 | ÷ | ( | 100 | + | 80 | ) |
| Multiply both sides of the equation by: | ( | 100 | + | 80 | ) |
1 5 | x | ( | 100 | + | 80 | ) | = | 10000 |
1 5 | x | × | 100 | + | 1 5 | x | × | 80 | = | 10000 |
| 20 | x | + | 16 | x | = | 10000 |
| 36 | x | = | 10000 |
| x | = | 10000 | ÷ | 36 |
| = | 10000 | × | 1 36 |
| = | 2500 | × | 1 9 |
| x | = | 2500 9 |
| x | = | 277.777778 |