Algorithms will use in/out/in-out to show the flow of data – but this is for design only.

Formal and Actual parameters only apply in the implementation.

Your “getinput” function does have data coming out, but it has NO parameters.

Your “calculate_area” function takes in two items of data, and sends out one item – but it has 2 formal parameters – length and width.

“display_area” has one formal parameter.

The actual parameters are in the main program.

length, breadth = get_inputs() has no parameters.

area = calculate_area(length, breadth) has two actual parameters (length and breadth) corresponding to the formal parameters in the function (also called length and breadth).