A stock list counts boxes, but the display needs individual items. Declare the conversion function above main so the compiler can check the call. Define it below main, where it can multiply boxes by items per box.
int items_in_boxes(int boxes, int per_box); before main and define it after main to return the product. Leave the supplied call unchanged: the complete output must be Items: 24 and a newline.The prototype has a semicolon and no body; the definition has the same types and a return statement.