Given that $x+y = 7$ and $3x+y = 45,$ evaluate $x^2-y^2.$
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Given that $x+y = 7$ and $3x+y = 45,$ evaluate $x^2-y^2.$
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
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Given that $x+y = 7$ and $3x+y = 45,$ evaluate $x^2-y^2.$
train