Help with Compound Assignment. Been stuck for a while

Tell us what’s happening:
I have read it over and over again. I do not know what is it that it wants.
I keeps highligting with the red X the part that says “You should use the += operator for each variable”

I am like I am using it! I have used it in several positions now. This is just one of the many ways I tried to used the operator “=+”

Your code so far

var a = 3;
var b = 17;
var c = 12;

// Only modify code below this line

var a += 3 + 12;
var b += 9 + 17;
var c += 12 + 7;

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Link to the challenge:

You don’t need to put the current value of variable to the right side of operator. Answer should be like

var a += 12;

and so on for other variables. This is because compound operator is already adding the value of a