Define the operation $\star$ by $a \star b = (a + b)b$. What is $(3\star5) - (5\star3)$?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Define the operation $\star$ by $a \star b = (a + b)b$. What is $(3\star5) - (5\star3)$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
16
Define the operation $\star$ by $a \star b = (a + b)b$. What is $(3\star5) - (5\star3)$?
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