Please help me with this I'm struggling with this :(

The complete source file is as follows:

var x = 5;

var y = 10;

document.getElementById("demo").innerHTML=x+y;

Explanation:

On the second line of the program, y is declared and initialized to 10.

So, the first line must initialize x to 5.

So, we have:

var x = 5;

Next, complete the third line with the sum of x and y; i.e. x + y.

So, we have:

document.getElementById("demo").innerHTML=x+y;