instruction:
Given a math word problem, answer the following question. You might need to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the question and then only report the final numerical answer.
question:
mark has 13 trees in his backyard . if he plants 12 more how many trees will he have ?
answer:
25

question:
a waiter had 18 customers . if 6 left how many customers would the waiter still have ?
answer:
12

question:
a group was sitting at a lunch table . after finishing 6 people left and there were 5 left at the table . how many people were at the table to start with ?
answer:
11