Evaluate $(x+y)(x-y)$ when $x=13$ and $y = 5$.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Evaluate $(x+y)(x-y)$ when $x=13$ and $y = 5$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
144
Evaluate $(x+y)(x-y)$ when $x=13$ and $y = 5$.
train