125

Code

   import java.io.File;
    import java.util.Scanner;
    
    public class SumThreeNumbers {
    
        public static void main(String[] args) throws Exception {
    
            int a, b, c;
            Scanner k = new Scanner(System.in);
            
            System.out.print("Which file would you like to read numbers from: ");
            String file = k.next();
            
            Scanner fileIn = new Scanner(new File(file));
    
            a = fileIn.nextInt();
            b = fileIn.nextInt();
            c = fileIn.nextInt();
    
            fileIn.close();
    
            int sum = a + b + c;
            System.out.println("\n" + a + " + " + b + " + " + c + " = " + sum);
            System.out.println();
        }
    }
    
  

Picture of the output