Program to calculate electricity bill of consumed units

#include <iostream>
#include <conio.h>
#include <stdlib.h>
using namespace std;

int main()
{
 //Program to calculate electricity bill of consumed units
 int units,curunits,preunits;
 float bill;
 cout<<"Enter the current reading =";
 cin>>curunits;
 cout<<"Enter the previous reading = ";
 cin>>preunits;
 units= curunits-preunits;
 if(units<100)
 bill = 2.0*units;
 if(units>100 && units<=200)
 bill = ((2.5*units)+(units*0.5/100.0));
 if(units>=200 &&units<=300)
 bill = ((3.5*units)+(units*0.6/100.0));
 if(units>400)
 bill=((4.0*units)+(units*0.7/100.0));
 cout<<"The electricity bill is ="<<bill;

getch();
    return 0;
 
}