Basic JavaScript - Understanding Uninitialized Variables

Tell us what’s happening:
Describe your issue in detail here.

what do i miss ?

Your code so far

// Only change code below this line
var a;
var b;
var c;

a = 5;
b = 10;
c = "i am";
// Only change code above this line

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

a = 6;
b = 15;
c = "i am a string!"

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Challenge: Basic JavaScript - Understanding Uninitialized Variables

Link to the challenge:

You made changes below this comment that tells you not no make changes, so that is probably a problem.