Shaquille, Lyle, and Amanda collect stamps. Shaquille has one-half the number of stamps that Lyle has. Amanda has two-thirds as many stamps as Lyle. Together they have 364 stamps. How many stamps does Amanda own?

Let Lyle have x stamps. Then Shaquille has x/2 and Amanda has 2x/3, so together they have x + x/2 + 2x/3 = 13x/6 stamps. Setting this equal to 364 gives x = 168, so Amanda has (2/3) × 168 = 112 stamps. The correct choice is 112.

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