constructor inheritance c++

#include<conio.h>
#include<iostream>
#include<string>
using namespace std;
class employ
{
      public:
      employ(const string &,const string &,double = 0.0);
      void First(const string &);
      string getName() const;
      void Second(const string  &);
      string GetSecnd() const;
      void add(double);
      double prize();
      private:
      string first_name;
      string last_name;
      double erning;
    
};

employ::employ(const string & first,const string  & last,double edit)
{
first_name=first;
last_name=last; 
add(edit);
 }
void employ::First(const string &first)
{
   first_name=first;
  
}
string employ::getName() const
{
                 return first_name;
}
void employ::Second(const string &last)
{
    last_name=last;
}
string employ::GetSecnd() const
{
return last_name;
}
void employ::add(double edit)
{
     if(edit > 300){
    
             erning=edit;
}
 else
 {
    
     cout << "sorry  menemom rupess 300";
 }
}
 double employ::prize()
 {
 return erning;
 }
int main()
{
    employ em("abdullah","masood");
    em.add(3000);
    cout << em.getName()<<"  "<<em.GetSecnd();
    cout << endl << em.prize();
    getch();
    return 0;
}