June Said:

Any advice on how to help my 3rd grader with this math question?

We Answered:

What a stupid question. Is it "wrong" if A and C are both 3? What about 5 and 1? 1 and 5? 2 and 4? 6 and 0?

Do you have any Lego bricks? To get the answer they "want", you'll need 12 of 1 colour and 6 of the other. Stick the "A" colour blocks tgether in 3 groups of 4, and the "C" colour in 3 groups of 2. Now just arrange them differently.

The left hand side is arranged as three separate lots of a group of 4 and a group of 2 stuck together.
The right hand side is arranged as all three groups of 4 stuck together and all three groups of 2 stuck together.

The important bit is that in both arrangements, there is the same total number of bricks.

Your daughter will probably point out that there are lots of other ways she could stick that many bricks together. _She is right_. Do _not_ let anyone tell her she is wrong. But do ask her if she can figure out how to write the other ways down as sums.