Derek is planning a road trip and needs to calculate his expenses. He starts with $500. He plans to spend $150 on gas, $200 on food, and $75 on lodging. Additionally, he wants to set aside $30 for emergency expenses and buy souvenirs worth three times the amount he sets aside for emergencies. How much money will Derek have left after accounting for all his expenses? Let's think step by step and output the final answer within \boxed{}.
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