bill program in c

#include<stdio.h>
int main()
{
int units,bills;
printf("enetyr your units");
scanf("%d",&units);
if(units<=20){


bills=units*2;

 printf("your bills %d\n",bills);}
 if((units>20)&&(units<=50))
{
bills=40+(units-20)*3;

   printf("your bills %d\n",bills);}
 if(units>50)
{

bills=130+(units-50)*5;

    printf("your bills %d\n",bills);}

system("pause");
return 0;
}