4.

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

const int   STD_HRS       = 40;
const float OVERTIME_MULT = 1.5;

int main()
{

   cout << setprecision(2);
   float hours, rate;
   cout << "Enter hours worked: ";
   cin  >> hours;
   cout << "Enter rate: ";
   cin  >> rate;
   float regular, overtime;
   if ( hours == STD_HRS )
   {
      regular  = hours * rate;
      overtime = 0.0;
   }
   else
   {
      regular  = STD_HRS * rate;
      overtime = (hours - STD_HRS) * OVERTIME_MULT;
   }
   float pay;
   pay = regular + overtime;
   cout << "Pay: $" << pay << endl;
   return 0;
}

OUTPUT:
Enter hours worked: 40
Enter rate: 8
Pay: $320.00