Answer:
Declaration for function 1:
void printHeading(String heading);
Declaration for function 2:
int yearPage(int currentYear, int birthYear);
Declaration for function 3:
void printable(String [] names, int [] birthDays, int size);
Explanation:
Prototypes of any function includes its return type followed by its name followed by list of arguments used by it enclosed within parenthesis.
Syntax for method declaration:
return_type function_name (list_of_arguments);