Is this the correct answer

No, it is not.

But, the good news is that you only made one small error. First, we can check our own work. Here's how.

Look what happens, when we use your value of 23 for A in the original equation (to check).

-A + 10 = 13

-23 + 10 = 13

-13 = 13

We do not end up with a true result. This tells us that the answer 23 is not correct.

You began by subtracting 10 from both sides

-A = 13 - 10 ? This is correct

Next, you multiplied both sides by -1

A = -13 - 10 ? You forgot to also multiply -10 by -1