You are given a math word problem and you are supposed to only use subtraction on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

Q: Context: A waiter had 13 customers. After some left he got 4 new customers. If he still had 9 customers 

 Question: How many customers left?

A: 8
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Q: Context: There were some roses in the vase. Jessica cut 16 more roses from her flower garden and put them in the vase. There are now 23 roses in the vase. 

 Question: How many roses were there in the vase at the beginning?

A: 7
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Q: Context: 2 birds were sitting on the fence. Some more birds came to join them. If there are a total of 6 birds on the fence now 

 Question: How many more birds had come to sit on the fence?

A:
4
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