Ok so I decided to give it a shot and help you out a little bit. I coded a portion of what you're looking for. I hope that's helpful.
I haven't implemented anything for double requests, therefore it only works for single requests.
Also, I'm not sure how is the "Total Cash" variable supposed to work. Is the user supposed to type the value he's going to pay?
Anyway, here it is: (The code has been tested)
Code:
#include <iostream>
#include <string>
using namespace std;
int main()
{
cout<<"SBC Restaurant" <<endl;
cout<<"Menu" <<endl <<endl <<endl;
cout<<"Food Item Price | Drink Item Price"<<endl <<endl;
cout<<"1 Fries 20$ | 7 Mineral Water 20$"<<endl <<endl;
cout<<"2 Hamburger 25$ | 8 Iced Tea 40$"<<endl <<endl;
cout<<"3 Cheese Burger 30$ | 9 Coke 35$"<<endl <<endl;
cout<<"4 Pizza 100$ | 10 Sprite 35$"<<endl <<endl;
cout<<"5 Chicken(p/piece) 50$ | 11 Sago 25$"<<endl <<endl;
cout<<"6 Spaghetti 40$ | 12 Taho 25$"<<endl <<endl <<endl <<endl;
char answer;
string name;
int norder[12], quantity, order;
double amount, change, cash;
norder[0] = 20;
norder[1] = 25;
norder[2] = 30;
norder[3] = 100;
norder[4] = 50;
norder[5] = 40;
norder[6] = 20;
norder[7] = 40;
norder[8] = 35;
norder[9] = 35;
norder[10] = 25;
norder[11] = 25;
cout<<"Customer Name: ";
cin>>name;
cout<<"Enter the Order: ";
cin>>order;
cout<<"Quantity: ";
cin>>quantity;
cout<<"Aditional Order (Y/N): ";
cin>>answer;
cout<<endl;
cin.ignore();
int price = *(norder + (order - 1));
cout<<"Customer name: " <<name <<endl;
cout<<"Total Amount: " <<price * quantity <<endl;
cout<<"Total Cash: " <<endl;
cout<<"Change: " <<endl <<endl;
cin.get();
}