Mary bought six apples from the store. From the apples she bought, for each that Mary ate, she planted two trees from the remaining ones. How many apples did Mary eat?
She planted eight trees. This means she used half of that amount of apples, which is 8 trees / 2 trees/apple = <<8/2=4>>4 apples.
That means that she planted four of the six apples she bought, leaving only 6 apples - 4 apples = <<6-4=2>>2 apples to be eaten.
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