Remark
The charge per day is 30 dollars. That is a one time charge. If you put an x there, you are going to modify the charge to something not intended. That makes both A and D incorrect.
Solution
The x must go with the miles. Again you can't put the x with the total charge. That would change the 130 to something else and that is not intended. B is incorrect.
The answer must be C.
