Use the Formula $i = P r t$ To Reach a Solution for the Following Problem

Multiple Choice

Use the formula $i = P r t$ to reach a solution for the following problem. How much is a month s interest on a mortgage balance of $2,640 at an 7% annual interest rate?

A) $185.80
B) $15.40
C) $184.80
D) $30.80
E) none of these