Answer:
6%
Explanation:
In order to calculate the interest that Mary paid on her loan, we must first calculate the increased interest by dividing her total paid by the initial loan like so...
$8,480 / $8,000 = 1.06
This is the increased interest rate in decimal form. Now we must subtract by 1 and multiply by 100 to turn this into a percentage.
(1.06 - 1) / 100 = 6%
Now we see that the total interest rate that Mary paid on her loan was 6% which would sum up to be $480 on top of her initial loan.
