Hi there, If you take 17.99, you can look at this as 18.00 because it's only one cent off. So if your not playing the full hour after the one in a half hour mark you can look at 18.00 and take away half of 18 which is 9 because for one hour you pay 17.99. And if you add 18.00 plus 9.00 you will get the total of 27.00. So I'm pretty sure the answer 27.00$.