You are given a math word problem and you are supposed to apply multiple mathematical operators like addition, subtraction, multiplication or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
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Question: Gwen bought two coloring books . One had 10 pictures and the other had 39 . After one week she had already colored 13 of the pictures . How many pictures does she still have to color ?

Answer: 36

Question: The cafeteria had 47 apples . For lunch they handed out 27 to students and decided to use the rest to make pies . If each pie takes 4 apples , how many pies could they make ?

Answer: 5

Question: A company invited 18 people to a luncheon , but 12 of them did n't show up . If the tables they had held 3 people each , how many tables do they need ?

Answer:
2