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 Q]: john is building a tree house to serve as his hideout whenever he wanted to spend some time alone with himself . the first thing he did is to gather some materials . for the pillars he needs 2 sets of wood with different lengths . if the first set of wood is 4 feet long and the second set is 5 times longer than the first set how long is the second set of wood ?
[EX A]: 20

[EX Q]: rachel bought 7 new chairs and 3 new tables for her house . if she spent 4 minutes on each piece furniture putting it together how many minutes did it take her to finish ?
[EX A]: 40

[EX Q]: the kids from oakwood elementary school are visiting a bird zoo for their field trip . to get to the bird zoo from the school the kids have to ride some buses . if there are 7 buses and each bus has 3 adult supervisors to guide the children how many supervisors are there in total ?
[EX A]:
21