Answer:
To check if the year comes under each 100th year, lets check if the remainder when dividing with 100 is 0 or not.
Similarly check for 400th year and multiple 0f 4. The following C program describes the function.
#include<stdio.h>
#include<stdbool.h>
bool is_leap_year(int year);
void main()
{
 int y;
 bool b;
  
 printf("Enter the year in yyyy format: e.g. 1999 \n");
 scanf("%d", &y);     // taking the input year in yyyy format.
  
 b= is_leap_year(y);  //calling the function and returning the output to b
 if(b==true)
 {
  printf("Thae given year is a leap year \n");
 }
 else
 {
  printf("The given year is not a leap year \n");
 }
}
bool is_leap_year(int year)
{
 if(year%100==0)   //every 100th year
 {
  if(year%400==0)   //every 400th year
  {
  	return true;
  }
  else
  {
  	return false;
  }
 }
 if(year%4==0)  //is a multiple of 4
 {
  return true;
 }
 else
 {
  return false;
 }
}
Explanation:
Output is given as image
 
        
             
        
        
        
Should be 1’ on each side
        
             
        
        
        
 Answer:
To determine which book titles have been purchased by a customer and when the order shipped the following tables and fields would be used.
Table:       
Fields 
Table
Fields:
Table: 
Fields:
Table:
Fields
BOOKS table contains field like title of the books, so this will help in finding which book titles have been purchased.
CUSTOMERS table keeps information about customers that purchasing an ordering the books. The customerno uniquely identifies each customer so that the order information can be found using the customerno of a specific customer.
ORDERITEMS keeps information about orders via orderno
ORDERS table will keep track about the shipment of orders. Orderno identifies each order, shipdate will help determine when an order is shipped.