In a grocery store, Julia bought 2 pieces of Snickers and 3 packs of M&M's. If each piece of Snickers costs $1.50 and a pack of M&M's has the same cost as 2 Snickers, how much is Julia's change if she gave the cashier 2 $10 bills? Let's think step by step and output the final answer within \boxed{}.
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