2009 IPE-1a question 3

#include <iostream>
using namespace std;
void input(double &BasicSalery, double &overtimeHours);
double calcSal(double BasicSalery,double overtimeAmount);
double calcOT(double overtimeHours);

int main()
{
double BasicSalery, overtimeHours, TotalSalery, overtimeAmount, PayRate, highest=0;
char ch = 'y';
while(ch=='y' || ch=='Y')
{
input(BasicSalery,overtimeHours);
overtimeAmount = calcOT(overtimeHours);
TotalSalery = calcSal(BasicSalery,overtimeAmount);

if(highest<TotalSalery)
highest = TotalSalery;

cout << "Do you have more data ? (y/n) : ";
        cin >> ch;
        while (ch != 'Y' && ch != 'N' && ch != 'y' && ch != 'n')
        {
             cout << "Please Type 'y' or 'n'\nDo you have more data ? (y/n) : ";
               cin >> ch;
        }

}
cout << "Highest Total Salery is " << highest << endl;
return 0;
}

void input (double &BasicSalery, double &overtimeHours)
{
cout << "Enter your basic salery : ";
cin >> BasicSalery;
cout << "Enter OT Hours : ";
cin >> overtimeHours;
while (overtimeHours<0 || overtimeHours>100)
{
cout << "Invalid OT Hours\nEnter OT Hours : ";
cin >> overtimeHours;
}
}
double calcSal(double BasicSalery,double overtimeAmount)
{
cout << "Your Total Salery is " << BasicSalery + overtimeAmount << " Rs." << endl;
return (BasicSalery + overtimeAmount);
}

double calcOT(double overtimeHours)
{
double PayRate;
if(overtimeHours<=20)
                PayRate = 100.0;
        else if(overtimeHours<=40 && overtimeHours>20)
                PayRate = 150.0;
        else if(overtimeHours<=60 && overtimeHours>40)
                PayRate = 200.0;
        else if (overtimeHours<=80 && overtimeHours>60)
                PayRate = 250.0;
        else
                PayRate = 300.0;
return overtimeHours*PayRate;
}