Rectangle class

[blackant]

I have to implement a complete class called Rectangle with 5 methods: Constructor, Show, Area, Merge and TotalArea.
I've done Constructor, Show, Area and Merge methods, but I stuck in TotalArea function. In this function, it takes an array of rectangle as a parameter. This method returns the sum of the areas of the rectangle in the array.

and this is my source code, the first is rectangle.h, and the second is rectangle.cpp

//rectangle.h
#include <string.h>	
#include <stdlib.h>	
#include <cstdlib>

class Rectangle
{
      public:
              Rectangle(double x, double y);
              
              ~Rectangle() {};
      private:
              double len;
              double wid;
              
      public:
             void Show(void);
             int Area(void);
             Rectangle Merge(Rectangle r);
             void TotalArea(void);
      };

//rectangle.cpp
#include <cstdlib>
#include <iostream>
#include "rectangle.h"

using namespace std;
Rectangle::Rectangle(double x, double y)
{
     len=x;
     wid=y;
     }     
void Rectangle::Show(void)
{
     cout<<"Leghth: "<<len <<"Width: "<<wid<<endl;
     }

int Rectangle::Area(void)
{
     double area;
     area=len*wid;
     
     }
Rectangle Rectangle::Merge(Rectangle r)
{
                  Rectangle d1(0.0,0.0);                
                  d1.len=len+r.len;
                  d1.wid=wid+r.wid;
                  return d1;
                  
};
     
int main(int argc, char *argv[])
{
    Rectangle r1(2.0, 3.0);
    Rectangle r2(7.0, 5.0);
    Rectangle r3(1.0, 1.0);
    
    r1.Show();
    
    cout <<"Area of r2: "<<r2.Area()<<endl;
    r3=r1.Merge(r2);
    r3.Show();
    /*
    Retangle allRects[2];
    allRects[0]=r1;
    allRects[1]=r2;
    cout<<"Total Area: "<<r2.TotalArea(allRects)<<endl;
    */
    system("PAUSE");
    return EXIT_SUCCESS;
}