Question 1121611
.
So, from your solution, the Ana's current age is 12.


Let me check it.


<pre>
    So, Maria is 36 years old now; Ana is 12 years old now.


    when Maria was as old as Ana is now ?


        - It was 24 years ago:  36 - 12 = 24.


    How old was Ana when Maria was as old as Ana is now ?


        - The answer is:  24 years ago Ana was  12 - 24 = - 12 years.
</pre>

It is a nonsense.


So you see (and I proved it to you) that the solution you came with is WRONG.