Understanding Uninitialized Variables misunderstanding

Tell us what’s happening:

I do not understand why my answer is not correct or why we cannot change the code below the line.

Your code so far


// Initialize these three variables
var a=6;
var b=15;
var c = "I am a string!";

// Do not change code below this line

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

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Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-javascript/understanding-uninitialized-variables