Answer
Principal (the amount borrowed/loaned), rate (the percent interest rate), and time that the money was borrowed/loaned.
Work Step by Step
We know that the interest formula is:
$I=P*r*t$
To calculate the interest, we need to know:
P=Principal (the amount borrowed/loaned)
r=rate (the percent interest rate)
t=time (in months, years, etc) that the money was borrowed/loaned
