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.

after a week sofia did a survey to ask if the students liked the new menu . she found out that 235 students liked the new menu while 165 did n't . how many students took part in sofia 's survey ?
400

there are 64 pigs in the barn . some more come to join them . now there are 86 pigs . how many pigs came to join them ?
22

kim wants to buy a new watch that costs $ 87.60 . how much change does she receive if she gives the cashier $ 100 ?
12.4