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

[Q]: Each bottle cap costs $ 5 . How much do 5 bottle caps cost ?
[A]: 25

[Q]: At lunch a waiter had 7 customers and 4 of them did n't leave a tip . If he got $ 9 each from the ones who did tip , how much money did he earn ?
[A]: 27

[Q]: Edward and his friend were buying trick decks from the magic shop for 9 dollars each . How much did they spend if Edward bought 4 decks and his friend bought 4 decks ?
[A]:
72