Basic JavaScript: Understanding Uninitialized Variables

Tell us what’s happening:

it won’t run the tests when i click the button?

Your code so far

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

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36.

Link to the challenge:

Your problem is likely to be caused by this line: that is not a string