Ошибка "error unresolved external"

class Tbike
{
public:
        
    Tbike();// Конструктор
    bool go(int km);
    bool pitstop(int fuel);
    float gettanksize();
    float getfuelsize();
    float getrun();
protected:
    float tanksize;
    float run;
    float fuelsize;
};

#include "Tbike.h"
#include <string.h>
#include <time.h>
#include <stdlib.h>
 
Tbike::Tbike()
{
    tanksize=30.0+rand()%20;
    fuelsize=tanksize-rand()%10;
    run=2.0;
 
}
 
bool Tbike::go(int km)
{
    float distance = fuelsize/run;
    
    if (distance>km)
    {   
        fuelsize=fuelsize-km*run;
        return true;
    }
    else
    return false;
}
 
bool Tbike::pitstop(int fuel)
{
    if ((fuelsize+fuel)<=tanksize)
    {   
        fuelsize=fuelsize+fuel;
        return true;
    }
    else
    return false;
}
 
float Tbike::gettanksize()
{
return tanksize;
}
 
float Tbike::getfuelsize()
{
return fuelsize;
}
float Tbike::getrun()
{
return run;
}

#include "Tbike.h"
 
class TCargo_bike:public Tbike
{
private:
    int cargo;
public:
    TCargo_bike();
    bool go_cargo(int km, int kg);
    int getcargo();
};

#include "TCargo_bike.h"
#include <string.h>
#include <time.h>
#include <stdlib.h>
 
TCargo_bike::TCargo_bike():Tbike()
{
    cargo=75+rand()%75;
}
 
bool TCargo_bike::go_cargo(int km, int kg)
{
    if (kg<=cargo)
    {
    bool rez;
    run++;
    rez= go(km);
    run--;
    return rez;
    }
    else
    return false;
}
 
int TCargo_bike::getcargo()
{
    return cargo;
}

#include <stdio.h>
#include "TCargo_bike.h"
#include <time.h>
#include <stdlib.h>
#include <string.h>
 
void main ()
{
    srand(time(0));
    
    TCargo_bike bike;
    int dist;
    int litrs;
    int kg;
    printf("Tanksize = %f\nfuelsize = %f\nrun/km = %f\n", bike.gettanksize(), bike.getfuelsize(), bike.getrun());
    printf("\nHow long distance?\n");
    scanf("%d", &dist);
    
    
    if (bike.go(dist))
        {
        printf("\nLet's go!\n");
        }
    else
        {
        printf("\nCan't go!\n");
        }
        
    printf("Tanksize = %f\nfuelsize = %f\nrun/km = %f\nCargo = %d\n", bike.gettanksize(), bike.getfuelsize(), bike.getrun(), bike.getcargo());  
 
    printf("\nHow many litrs?\n");
    scanf("%d", &litrs);
    
    if (bike.pitstop(litrs))
    printf("\nOk! You have %f litrs\n", bike.getfuelsize());
    else
    printf("Can't zapravit' malyi bak!");
    
    printf("\nHow many kg?\n");
    scanf("%d", &kg);
    
    if (bike.go_cargo(dist, kg))
        printf("\nGo)\n");
    else
        printf("\nCan't go\n");
    
    printf("Tanksize = %f\nfuelsize = %f\nrun/km = %f\n", bike.gettanksize(), bike.getfuelsize(), bike.getrun());
}