Fractionクラスを用いた四則演算

47:error: ‘Fraction operator/(Fraction)’ must take exactly two arguments
91:error: no match for ‘operator-’ in ‘f1 - f2’
45:note: candidates are: Fraction operator-(Fraction)
92:error: no match for ‘operator*’ in ‘f1 * f3’
46:note: candidates are: Fraction operator*(Fraction)
93:error: no match for ‘operator-’ in ‘f1 - f4’
45:note: candidates are: Fraction operator-(Fraction)
94:error: no match for ‘operator/’ in ‘f2 / f4’
95:error: no match for ‘operator/’ in ‘f2 / f5’
96:error: no match for ‘operator*’ in ‘f6 * f2’
46:note: candidates are: Fraction operator*(Fraction)

上記のエラーの意味がググりましたがよく分かりませんでした。よろしければご回答いただけると幸いです。
#include<iostream>
using namespace std;

class Fraction{
private:
  int bunsi,bunbo;
public:
  Fraction(int x,int y){
    if(bunbo<0) bunsi*=-1;bunbo*=-1;
    if(x==y) y=1;
    bunsi=x;
    bunbo=y;
  }
  
  Fraction(int x){bunsi=x;bunbo=1;}
  Fraction(){bunsi=0,bunbo=1;}
  int gcd_o(int bunsi,int bunbo){
    int r;
    while((r=bunsi%bunbo)!=0){
      bunsi=bunbo;
      bunbo=r;
    }
    return bunbo;
  }

  void set_F(int x,int y){
    bunsi=x;
    bunbo=y;
  }  
   void reduce(Fraction x){
    
    int z=gcd_o(x.bunsi,x.bunbo);
    if(0>z) z*=-1;
    set_F(x.bunsi/z,x.bunbo/z);
  }
  friend Fraction operator+(const Fraction x,const Fraction y);
  friend Fraction operator-(Fraction x);
  friend Fraction operator*(Fraction x);
  friend Fraction operator/(Fraction x);
  friend ostream& operator<<(ostream& ost,Fraction x);
};

Fraction operator+(const Fraction x,const Fraction y){
 
  return Fraction(x.bunsi*y.bunbo+x.bunbo*y.bunsi,x.bunbo*y.bunbo);
}

Fraction Fraction::operator-(Fraction x){
  return Fraction(bunsi*x.bunbo-bunbo*x.bunsi,bunbo*x.bunbo);
}

Fraction Fraction::operator*(Fraction x){
  return Fraction(bunsi*x.bunsi,bunbo*x.bunbo);
}

Fraction Fraction::operator/(Fraction x){
  int a,b;
  a=bunsi*x.bunbo;
  b=bunbo*x.bunsi;
  if(b<0) a*=-1;b*=-1;
  return Fraction(a,b);
}

ostream& operator<<(ostream& ost,Fraction x){

  if(x.bunbo==1 || x.bunsi==0){
    x.reduce(x); 
    ost<<x.bunsi;
    }
  
  else{
    x.reduce(x); 
    ost<<"("<<x.bunsi<<"/"<<x.bunbo<<")";
  } 
  return ost;
}

int main(){
  const Fraction f1(1,2),f2(2,3),f3(2);
  Fraction f4(2,4),f5(-3,5),f6(0);
  Fraction g1,g2;
  cout<<f1<<"+"<<f2<<"="<<f1+f2<<"\n";
  cout<<f1<<"-"<<f2<<"="<<f1-f2<<"\n";
  cout<<f1<<"*"<<f3<<"="<<f1*f3<<"\n";
  cout<<f1<<"-"<<f4<<"="<<f1-f4<<"\n";
  cout<<f2<<"/"<<f4<<"="<<f2/f4<<"\n";
  cout<<f2<<"/"<<f5<<"="<<f2/f5<<"\n";
  cout<<f6<<"*"<<f2<<"="<<f6*f2<<"\n";
  cout<<1<<"+"<<f5<<"="<<1+f5<<"\n";
  /*cout<<"分数を入力-->"; cin>>g1;
  cout<<"分数を入力-->"; cin>>g2;
  if(g1>g2)cout<<g1<<">"<<g2<<"/n";
  if(g1<g2)cout<<g1<<"<"<<g2<<"/n";
  if(g1==g2)cout<<g1<<"=="<<g2<<"/n";
  cout<<g1<<"*"<<g2<<"="<<g1*g2<<"/n";
  cout<<g1<<"*"<<20<<"="<<g1*20<<" ";
  cout<<20<<"*"<<g1<<"="<<20*g1<<"/n";*/
  return 0;
}

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