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

[Q]: At the schools book fair Sam bought 13 adventure books and 17 mystery books . If 15 of the books were used , how many new books did he buy ?
[A]: 15


[Q]: There are 11 rulers and 34 crayons in the drawer . Tim placed 14 rulers in the drawer . How many rulers are now there in all ?
[A]: 25


[Q]: There are 42 walnut trees and 12 orange trees currently in the park . Park workers had to cut down 13 walnut trees that were damaged . How many walnut trees will be in the park when the workers are finished ?
[A]:
29