3. Write a declaration that, in the class in which it appears, will make every member of the class Aeroplane a friend function. 3 using namespace std; 4 5 class Number 6 7 private: 8 int a; public: 10 void getNum(int x); 11 void printNum (Number NUM); 12 }; 13 14 //class member function definitions 15 void Number::getNum(int x) 16 el 17 a=x; 18 } 19 20 void printNum (Number NUM) 21 22 cout