Percentages are ratios of an amount compared to 100. The percent change of an old to new value is equal to 100% x \({ new - old \over old }\).
Alex loaned Frank $400 at an annual interest rate of 9%. If no payments are made, what is the interest owed on this loan at the end of the first year?
| $60 | |
| $28 | |
| $5 | |
| $36 |