100000 | = | 21990 | ÷ | ( | 1 | + | r | ) |
Multiply both sides of the equation by: | ( | 1 | + | r | ) |
100000 | ( | 1 | + | r | ) | = | 21990 |
100000 | × | 1 | + | 100000 | r | = | 21990 |
100000 | + | 100000 | r | = | 21990 |
100000 | r | = | 21990 | − | 100000 |
100000 | r | = | - | 78010 |
r | = | - | 78010 | ÷ | 100000 |
= | - | 78010 | × | 1 100000 |
= | - | 7801 | × | 1 10000 |
r | = | - | 7801 10000 |
r | = | - 0.7801 |