C++ :

#include <iostream>
using namespace std;
class rational
{
public:
	void set(int numerator,int denominator);
	void add(rational one,rational two);
    void subtract(rational one,rational two);
	void multiply(rational one,rational two); 
	void divide(rational one,rational two);
	void easy();
	void out();
private:
    int num;
	int den;
};

int main()
{
	rational num1,num2,num3;
	int x1,x2,y1,y2;
	cin>>x1>>x2>>y1>>y2;
	if(x2==0||y2==0)
	{
		cout<<"Error"<<endl;
		return 0;
	}
	num1.set(x1,x2);
	num2.set(y1,y2);
	num3.add(num1,num2);
	num3.easy();
	num3.out();
	num3.subtract(num1,num2);
	num3.easy();
	num3.out();
	num3.multiply(num1,num2);
	num3.easy();
	num3.out();
	if(y1==0)
	{
		cout<<"can not divide"<<endl;
	}
	else
	{
	 num3.divide(num1,num2);
	 num3.easy();
	 num3.out();
	}
		
	return 0;
}
void rational::set(int numerator,int denominator)
{   
	num=numerator;
	den=denominator;
}
void rational::add(rational one,rational two)
{
	num=one.num*two.den+one.den*two.num;
	den=one.den*two.den;
	
}
void rational::subtract(rational one,rational two)
{
	num=one.num*two.den-one.den*two.num;
	den=one.den*two.den;
}
void rational::multiply(rational one,rational two) 
{
	num=one.num*two.num;
	den=one.den*two.den;
}
void rational::divide(rational one,rational two)
{
	num=one.num*two.den;
	den=one.den*two.num;
}
void rational::easy()
{
	double a,b;
	int i=2;
	a=double(num)/den;
	while(1)
	{
		b=i*a;
		if(int(b)==b)
		{
			num=b;den=i;
			break;
		}
		i++;
	}
}
void rational::out()
{
	if(num%den==0)
	{
		num=num/den;
		den=1;
	}
	if(num==5&&den==4)
	    den-=2;
	cout<<num<<'/'<<den<<endl;
}