How to calculate in C++?? PLS HELP ME?

How to calculate in C++?? PLS HELP ME?

How to compute financial ratio in C++ with using header file?
Calculate in c++ program with 3 different file. - 2 file (cpp file) - 1
file (header file)
Information:
formula:- *1.*Current ratio = (current asset / current liabilities)
*2.*Gross margin = (Revenue – Cost of goods sold) / Revenue *3.*Operating
margin= (Operating Income / Revenue) *4.*Profit margin = (Net Profit /
Revenue) *5.*ROE= (Net Income/Shareholder's Equity)
I want put 5 formula to run the program. How to put 5 formula in the
program but run one formula.
EXAMPLE: In the coding, write all financial ratio. When we compile, just
asking 1 formula value only. We need to fixed, which formula to run. Just
adjust the coding only. HOW?? pls help.
Please correct me If I'm wrong. I just start study C++ program.