//C++ Primer Plus -- Chapter 3--5
#include <iostream>
int main ()
{
using namespace std;
long double world;
cout<<"Enter the world's population:";
cin>>world;
cout<<"Enter the population of the USA:";
long double usa;
cin>>usa;
cout<<"The population of the US is "<<usa/world*100<<"% of the world population."<<endl;
return 0;
}