need help with C program using xCode

Part II: (70 pts) This program will use If logic to compute cost for ISP service depending on the user's plan. Submit a printout of the source code file and the screen shot of output. Grading policies concerning commenting and program design are the same as previous assignments and will not be repeated in successive assignments. An ISP offers three packages: Package A For $9.95 per month 10 hours of access are provided. Additional hours cost $2.00/hour. Package B For $14.95 per month 20 hours of access are provided. Additional hours cost $1.00/hour. Package C: For $19.95 per month unlimited access is provided. Input The user will enter a character code for their ISP package, the number of hours used in the month and the month number (1 12). If the user enters an invalid package code, invalid month number, or an invalid number of hours for the month, display an error message and end the program. A list of month numbers and the number of days in the month is listed below: January1 February 28 31 30 31 30 31 31 30 31 30 September 9 November 11 December 12 Your name should be the first line of output. Produce an attractive bill that lists the package code, number of hours, and cost. The precision should be set to show two places to the right of the decimal. Columns should be aligned using field widths versus tabs or blanks. The company wishes to encourage customers to select the best plan. For package A users, compute whether the user would have saved money using either package B or package C. If so, display the costs for these packages and the savings. For package B users, compute whether the user would have saved money using package C. If so, display the cost for this package and the savings. Note: You do not need to test for any other combinations