1.

#include <iostream>
using namespace std;

class Boat;
class Car {
private:
	int weight;
public:
	Car(int j) {
		weight = j;
	}
	friend int getTotalWeight(Car &aCar, Boat &aBoat);
};

class Boat {
private:
	int weight;
public:
	Boat(int j) {
		weight = j;
	}
	friend int getTotalWeight(Car &aCar, Boat &aBoat);
};

int getTotalWeight(Car &aCar, Boat &aBoat) {
	return aCar.weight + aBoat.weight;
}

int main() {
	Car c1(4);
	Boat b1(5);

	cout << getTotalWeight(c1, b1) << endl;
 return 0;
}

2.

#include <iostream>
using namespace std;

void fn1(); 
int x = 1, y = 2; 

int main()
{
	cout << "Begin..." << endl;
	cout << "x = " << x << endl;
	cout << "y = " << y << endl;
	cout << "Evaluate x and y in main()..." << endl;
	int x = 10, y = 20;
	cout << "x = " << x << endl;
	cout << "y = " << y << endl;
	cout << "Step into fn1()..." << endl;
	fn1();
	cout << "Back in main" << endl;
	cout << "x = " << x << endl;
	cout << "y = " << y << endl;
	return 0;
}
void fn1()
{
    int y = 200;
    cout << "x = " << x << endl;
    cout << "y = " << y << endl;
}

3.

#include "client.h"

void Client::ChangeServerName(char name) {
	Client::ServerName = name;
	Client::ClientNum ++;
}
int Client::getClientNum() {
	return Client::ClientNum;
}

#ifndef CLIENT_H_
#define CLIENT_H_

class Client {
	static char ServerName;
	static int ClientNum;
public:
	static void ChangeServerName(char name);
	static int getClientNum();
};


#endif

#include <iostream>
#include "client.h"
using namespace std;

int Client::ClientNum = 0;
char Client::ServerName = 'a';

int main()
{
	Client c1;
	c1.ChangeServerName('a');
	cout << c1.getClientNum() << endl;
	Client c2;
	c2.ChangeServerName('b');
	cout << c2.getClientNum() << endl;
	return 0;
}