There are a whole lot of things to be pointed out in your code-
1. This is not a C++ code, it's perfectly C, so you posted in a wrong section.
2. There is nothing called "iint" in C.
3. Comment your code properly. If you've started with /* so you should end up with */ not //. // is a single line comment used with one lines only. For eg. here is a single line comment:
4. As tabstop mentioned change 5/9 and 9/5 to 5.0/9 and 9.0/5.int i; //this is a comment
5. Use proper format specifier to print the required value. eg %f in you case.
6. It would be better not to make global declarations for all the variables.