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.

mike had 51 books but he sold 45 at a garage sale . how many books does mike still have ?
6

gwen prepared 98 books to sell in the flea market . after the activity ended she had 96 books left . how many did she sell ?
2

john had 33 socks . if he threw away 19 old 1 that did n't fit and bought 13 new 1 how many socks would he have ?
27