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: Randy has 86 blocks. He uses 79 blocks to build a tower and 82 blocks to build a house. 

 Question: How many more blocks did he use to build the house than he did to build the tower?
[A]: 3


[Q]: Context: 53 campers went rowing in the morning 48 campers went rowing in the afternoon and 49 campers went rowing in the evening. 

 Question: How many more campers went rowing in the morning than in the evening?
[A]: 4


[Q]: Context: Danny collects bottle caps and wrappers. He found 82 wrappers and 29 bottle caps at the park. Now he has 42 bottle caps and 61 wrappers in his collection. 

 Question: How many bottle caps did danny have at first?
[A]:
13