scheme programming error checking

I have attached the program. I partially misunderstood the assignment when I wrote the program, and now I cannot figure out how to correct the program. The program is a Scheme compiler that simplifies expressions according to the 20 rules given by the assignment. I have been running the program in DrRacket 5.3.3. Once loaded into DrRacket, the program works as follows: I enter the expression to be evaluated as a list: > (parse '(+ 2 3)) The program outputs the following: (+ 2 3) 5 This expression is simplified according to Rule 1, and in this case the program is functioning properly. The program functions properly for rules that only involve c, where c represents a constant which in this case is any integer. The program cannot correctly evaluate expressions which include a "t". The program should be able to evaluate expressions where t represents a variable or another s-expression. For example if I enter the following expression: (parse '(+ (+ 3 t) 2)) The program output should be: (+ (+ 3 2) t) (+ 5 t) Could you help me figure out how to correct this? I am sure that you have questions. Please let me know. Thank you. please download the file from the link below [login to view URL] pay 20$ for error checking the code