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.

debby owned 13 dvds . if she sold 6 of them how many would she have left ?
7

dan has $ 3 . he bought a candy bar for $ 1 . how much money is left ?
2

after the final bell rang buddy ran to the school bus with his new friends . on his ride home he counted 36 students sitting on the left side of the bus and 27 sitting on the right . how many students are on the bus ride home ?
63