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

Example Input: A restaurant made 9 hamburgers to serve during lunch . Only 3 were actually served . How many hamburgers were over from lunch ?
Example Output: 6

Example Input: Keith has 20 books . Jason has 21 books . How many books do they have together ?
Example Output: 41

Example Input: There are 6 pencils and 7 rulers in the drawer . Benny placed 3 pencils in the drawer . How many pencils are now there in total ?
Example Output:
9