Understanding Uninitialized Variables Emergency!

Tell us what’s happening:
Hey guys, i need help… I have tried passing this code but i don’t understand why it’s failing.

Your code so far

// Initialize these three variables
var a;
var b;
var c;

// Do not change code below this line

a = a + 1;
b = b + 5;
c = c + " String!";

var a = a + 5;
var b = b + 10;
var c = "I am a String!";

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 6.2; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36.

Link to the challenge:

There is a line in your code that does say

Do not change code below this line

Other than that, you can’t initialise a variable with var after having already used it. You can’t use a variable without giving it a value before (when you write a+5, a doesn’t have a value, so you are writing undefined + 5)

You need to give a value to the variables when they are initialised (when they are called for the first time with var a for example)

As ieaheen says, a variable that has no value you can’t use it.

You should (probably) set a value above the second commented line.
Once you have initialized the var, you can use it to make any operations