Let's assume, for now, that it will take at most a year for him to repay the total cost. Therefore, regarding the information on the card, there will be no interest in this bill.
Now, to find the number of months it will take, we can divide the total cost (2,367.42) by the amount he pays each month (215.22):
[tex]\frac{2367.42}{215.22}=\frac{236742}{21522}=11[/tex]As 11 months is less than one year, there won't be any interest by the credit card indeed. So 11 months is the correct answer.