根據(jù)句子意思列出算式，并計(jì)算出正確答案。

Joy has eleven books.

His father buys five books for him.

How many books does Joy have now？

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Sam has thirteen apples in a bag.

Ben takes four apples away.

How many apples does Sam have now？

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There are nine boxes of chocolate on a table.

A woman puts six more boxes of chocolate on the table.

How many boxes of chocolate are there now？

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There are twenty bottles of juice in a store.

A man takes seven bottles of juice away.

How many bottles of juice are left in the store？

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