Definition: 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.
Input: lana 's mom was buying extra school supplies for her and her siblings . if she bought 3 packs of glue sticks with 7 glue sticks in each pack how many did she get total ?
Output:
21