Basic JavaScript - Compound Assignment With Augmented Addition

Tell us what’s happening:
Describe your issue in detail here.
my run test button is not working at all nor the ctrl+enter and I had b += 9 before and somehow it was flipped then I had it this way
let a = 3;

let b = 17;

let c = 12;

// Only change code below this line

15 += a = 12;

26 += b = 9;

19 += c = 7;
can someone please help and I also went to the next assignment and it is doing the same thing

Your code so far

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

// Only change code below this line
15 = a += 12;
26 = 9 += b;
19 = c += 7;

Your browser information:

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Challenge: Basic JavaScript - Compound Assignment With Augmented Addition

Link to the challenge:

Did you see the error message in the console?

SyntaxError: unknown: Invalid left-hand side in assignment expression. (6:0)

  4 |
  5 | // Only change code below this line
> 6 | 15 = a += 12;
    | ^
  7 | 26 = 9 += b;
  8 | 19 = c += 7;

You cannot put a constant on the left side of an assignment expression. The number 15 will always be 15, but a line starting with 15 = tells the computer to change 15 to equal some value on the right side, which is impossible, so the whole program will crash.

Your assignment expressions should always start with a variable, because only the value of a variable can vary (hence the name).

If you have a variable a with a value of 10, and you want to make it equal 15 via addition, you can enter a = a + 5; or a += 5; . The line a = a + 12; adds 12 to the value of a and assigns the new value to a. How can you simplify that line using the += operator?

Here is some code you can start with to help you keep track of the final values of your variables:

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

// Only change code below this line
a = a + 12;
b = 9 + b;
c = c + 7;

console.log("a == "+a);
console.log("b == "+b);
console.log("c == "+c);

i got ty so much much appreciated