Pls what wrong with my code it's not working

Tell us what’s happening:

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!";
a = 6;
b = 15;
c = "I am a!";




 

 





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Link to the challenge:
https://www.freecodecamp.org/challenges/understanding-uninitialized-variables

Only change code above this:

// Do not change code below this line