I don't know if it's just me but the wording was super confusing.

in C# this works

  // Declare second integer, double, and String variables.
    int secondInteger;
    double secondDouble; 
    string secondText;

    // Read and save an integer, double, and String to your variables.
     secondInteger = int.Parse(Console.ReadLine());
     secondDouble = double.Parse(Console.ReadLine());
     secondText = Console.ReadLine();

    // Print the sum of both integer variables on a new line.
    Console.WriteLine(secondInteger+i);

    // Print the sum of the double variables on a new line.
    double var3 = secondDouble+d;
     Console.WriteLine(var3.ToString("F1"));

    // Concatenate and print the String variables on a new line
    // The 's' variable above should be printed first.
    Console.WriteLine(s+""+secondText);


}

here is Day 1 data types solution in python, java, c++, c and javascript - https://programmingoneonone.com/hackerrank-day-1-data-types-30-days-of-code-solution.html

The task says:

The variables i d and s are already declared and initialized for you.

But this is not true, You'll need to create and initalise them yourself to pass.

Eg:

const i: number = 4;
const d: number = 4.0;
const s: string = "HackerRank"

`

This is correct code but still icant figure it out why do we taken that i & d as 4 can anybody** help me **with that .

    int i = 4;
    double d = 4.0;
    String s = "HackerRank ";

    Scanner scan = new Scanner(System.in);

    int i2 = scan.nextInt();      
    double d2 = scan.nextDouble();
    scan.nextLine();              
    String s2 = scan.nextLine();  


    System.out.println(i + i2);
    System.out.printf("%.1f\n", d + d2);
    System.out.println(s + s2);

    scan.close();
}

}