-125
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the value of $(x - y)(x + y)$ if $x = 10$ and $y = 15$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
-125
What is the value of $(x - y)(x + y)$ if $x = 10$ and $y = 15$?
train