Let's say that Gia starts with an amount of money we can call x. By spending 2/5 of her money (or (2/5)x) on a shirt, her money is now x-(2/5)x=(5/5)x-(2/5)x=(3/5)x. That is her remaining money. To find 4/9 of her remaining money, we must multiply her remaining money by 4/9 to get (3/5)x*4/9=(12/45)x. Therefore, Gia spends (12/45) of her original amount on a pair of shoes. We must subtract that from (3/5) to get her final amount of (3/5)x-(12/45)x=(27/45)x-(12/45)x=(15/45)x=(1/3)x as her remaining money, so your answer is 1/3
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