Answer:
The following will be used:
#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;
int main() {
 double total = 0;
 int nTickets = 0;
 ifstream infile("tickets.txt");
 ofstream outfile("output.txt");
 int a,b;
 while (infile >> a >> b)
 {
   total += a*b;
   nTickets = nTickets + b;
 }
 outfile << "Total Sale amount: " << setprecision(2) << total << endl;
 outfile << "Number of tickets sold: " << nTickets << endl;
 outfile.close();
 cout<<"See output file: output.txt for the results."<<endl;
 return 0;
}