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

Example Input: The school cafeteria ordered 42 red apples and 7 green apples for students lunches . But , if only 9 students wanted fruit , how many extra did the cafeteria end up with ?
Example Output: 40

Example Input: In fourth grade there were 10 students at the start of the year . During the year 4 students left and 42 new students came to school . How many students were in fourth grade at the end ?
Example Output: 48

Example Input: Dave bought 12 boxes of chocolate candy and gave 5 to his little brother . If each box has 3 pieces inside it , how many pieces did Dave still have ?
Example Output:
21