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.

Ex Input:
A chef needs to cook 9 potatoes . He has already cooked 7 . If each potato takes 3 minutes to cook , how long will it take him to cook the rest ?

Ex Output:
6

Ex Input:
Each chocolate bar in a box cost $ 4 . If a box had 8 bars total and Emily sold all but 3 bars , how much money would she have made ?

Ex Output:
20

Ex Input:
A store had 40 coloring books in stock . They ended up putting them on sale and getting rid of 20 of them . The put the ones they still had onto shelves with 4 on each shelf . How many shelves did they use ?

Ex Output:
5