Answer:
#include <iostream>
using namespace std;
void findDuplicate(int arr[], int size) {
   for(int i = 0; i < size; ++i) {
       for(int j = i+1; j < size; ++j) {
           if(arr[j] == arr[i]) {
               cout << arr[j] << endl;
               return;
           }
       }
   }
   cout << -1 << endl;
}
int main() {
   int arr[] = {2, 3, 5, 6, 11, 20, 4, 8, 4, 9};
   findDuplicate(arr, 20);
   return 0;
}
Explanation:
 
        
             
        
        
        
The problem domain layer addresses how the software will execute on specific computers and networks.
A problem domain is a software engineering term that refers to all information that defines a problem and compels the solution.
A problem domain basically looks at only the area you are interested in and excludes the rest. It includes the goals the problem owner wishes to have and the context in which the problem exists. For example, if you are creating a website for selling artwork online, the problem domain will be artwork and eCommerce.
 Therefore, in order to identify a problem domain, you need to know the relevant user requirements. This can be easy when you start by finding out what people (users) think the problem is. 
#SPJ4
 
        
                    
             
        
        
        
The  storage that is used to store data in the computer's memory that can be used by a program later when executing instructions is variables.
<h3>What is variables?</h3>
Variables can be defined as the way or process in which data or information are store in a computer memory.
Data or information that may likely change or be altered are often stores in a computer memory storage called variables and this store data can be retrieve later for use by a program when executing instruction on the computer  system.
Inconclusion the  storage that is used to store data in the computer's memory that can be used by a program later when executing instructions is variables.
Learn more about variables here:brainly.com/question/23931018
 
        
             
        
        
        
I’m pretty sure it’s “Find and paste”