Typically, interest is charged by month and since this problem doesn't say anything about compound interest, we'll treat it as simple. We can just simply multiply 1500 and 0.23 to get the total amount of interest. The total amount of interest is 345. Assuming that the $123 to be paid monthly doesn't include the interest yet, Zeki has to pay 345 in total. At the end of the 15 months, he would have paid 345.
