12
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
If $a+b = 6$ and $a - b = 2$, what is the value of $a^2 - b^2$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
12
If $a+b = 6$ and $a - b = 2$, what is the value of $a^2 - b^2$?
train