C++ project need help ASAP

Question

https://drive.google.com/file/d/1jvrO_gRFyoi0gVTM8ZXR-B1OOzHnlJNi/view?usp=sharing

#include<iostream>
#include<iomanip>
using namespace std;

int count;
struct info
{

double yTax;
double priceIY;
double priceEY;
double gst;
double priceGST;
double DifferencePrice;
};

double Calculate(double&);

double Calculate(double &a,double &b,double &c )
{
info a;
a=S.priceEY=S.priceIY*(1.00-0.05);
a=S.priceGST=S.priceEY(1.00+0.06);
a=S.DifferencePrice=S.priceGST-S.priceIY;
return a;
}
{
info b='P';

P.priceEY=P.priceIY*(1.00-0.05);
P.priceGST=P.priceEY(1.00+0.06);
P.DifferencePrice=P.priceGST-P.priceIY;
return Calculate;
}
{
info c='Z';

Z.priceEY=Z.priceIY*(1.00-0.05);
Z.priceGST=Z.priceEY(1.00+0.06);
Z.DifferencePrice=Z.priceGST-Z.priceIY;
return Calculate;
}

int main()
{
struct info S, P, Z;
char lable;
int n;
cout<<"Enter the number of data you want to enter or '-1' to exit:";
cin>>n;
if(n == -1){
cout<<"You exited!";
return n;
}

for(int i=0;i<n;i++)
{
cout<<"Enter a lable or 'N' to exit : ";
cin>>lable;
if (lable == 'S' || lable == 's')
{

cout << "Item price: RM";
cin >>S.priceIY;
}
else if (lable == 'P' || lable == 'p')
{

cout << "Item price: RM";
cin >>P.priceIY;
}
else if (lable == 'Z' || lable == 'z')
{

cout << "Item price: RM";
cin >>Z.priceIY;
}
else if (lable == 'N' || lable == 'n')
break;
else
cout << "Invalid item label!" << endl;
}
return 0;
}

Answer 1

how to fix the fuction part?

Answer 2

some information about the coding.

https://drive.google.com/file/d/1NS2FjIHOmcpsj-kqN1Ee3khtbZyr8S-J/view?usp=sharing
https://drive.google.com/file/d/1HjBmSzIYIhofksehePVtxFpAGvuB_vok/view?usp=sharing
https://drive.google.com/file/d/1tVj6E8ehzgnYzdEp8x7rg6zyoeRwZNtL/view?usp=sharing
https://drive.google.com/file/d/1E8dTY9T7KI0f22iJE5a2pJX16sgS0MIK/view?usp=sharing
https://drive.google.com/file/d/1ufxuUOzJ5M36AbCm0hpg6jrusoDS2RLZ/view?usp=sharing