I have been told to write a program which calculates total cost using values for amounts of resources and cost. I am supposed to write the program in functions, which I understand how to do although I am told I cannot use global variablesn and don't need to use local variables.

But I don't understand how I can do the arithmetic without variables, and also how to pass the values between the functions without using global variables.

I am new to programming so I am sorry for asking questions which are probably very basic, I have had a quick look through the FAQ's and tutorials but I still can't seem to find anything that would help me.

Thanks