Business customers pay $0.006 per gallon for the first 8000 gallons. if the usage is more than 8000 gallons, the rate will be $0.008 per gallon after the first 8000 gallons. for example, a residential customer who has used 9000 gallons will pay $30 for the first 6000 gallons ($0.005 * 6000), plus $21 for the other 3000 gallons ($0.007 * 3000). the total bill will be $51. a business customer who has used 9000 gallons will pay $48 for the first 8000 gallons ($0.006 * 8000), plus $8 for the other 1000 gallons ($0.008 * 1000). the total bill will be $56. write a program to do the following. ask the user which type the customer it is and how many gallons of water have been used. calculate and display the bill.

#include <bits/stdc++.h>

using namespace std;

int main()

{

   // variables

   char cust_t;

   int no_gallon;

   double cost=0;

   cout<<"Enter the type of customer(B for business or R for residential):";

   // read the type of customer

   cin>>cust_t;

   // if type is business

   if(cust_t=='b'||cust_t=='B')

   {

       cout<<"please enter the number of gallons:";

       // read the number of gallons

       cin>>no_gallon;

       // if number of gallons are less or equal to 8000

       if(no_gallon<=8000)

       {

           // calculate cost

           cost=no_gallon*0.006;

           cout<<"total cost is: $"<<cost<<endl;

       }

       else

       {

           // if number of gallons is greater than 8000

           // calculate cost

           cost=(8000*0.006)+((no_gallon-8000)*0.008);

           cout<<"total cost is: $"<<cost<<endl;

       }

   }

   // if customer type is residential

   else if(cust_t=='r'||cust_t=='R')

        {

       cout<<"please enter the number of gallons:";

       // read the number of gallons

       cin>>no_gallon;

       // if number of gallons are less or equal to 8000

       if(no_gallon<=8000)

       {

           // calculate cost

           cost=no_gallon*0.007;

           cout<<"total cost is: $"<<cost<<endl;

       }

       else

       {// if number of gallons is greater than 8000

       // calculate cost

           cost=(8000*0.005)+((no_gallon-8000)*0.007);

           cout<<"total cost is: $"<<cost<<endl;      

       }        

   }

return 0;

}

Explanation:

Ask user to enter the type of customer and assign it to variable "cust_t". If the customer type is business then read the number of gallons from user and assign it to variable "no_gallon". Then calculate cost of gallons, if  gallons are less or equal to 800 then multiply it with 0.006.And if gallons are greater than 8000, cost for  first 8000 will be multiply by 0.006 and  for rest gallons multiply with 0.008.Similarly if customer type is residential then for first 8000 gallons cost will be multiply by 0.005 and for rest it will  multiply by 0.007. Then print the cost.

Output:

Enter the type of customer(B for business or R for residential):b                                                                                            

please enter the number of gallons:9000                                                                                                                      

total cost is: $56  

the answer is d underlined.