what's the answer to this

I think this is what you mean:

To solve this, we can use the rule:

So now we have:

So our answer is a⁶

Yes, I agree with NinjaDevo. The answer is  $$a^6$$ . 

Steps to solve the problem:

Step 1) Change (a^3)2 into  a^3*2. 

Step 2) Multiply 3 by 2.  $$a^3*2=a^6$$ .

Step 3) Your answer is  $$a^6$$ .

Hope it helps!