[Question]: Jennifer bought twice as many candies as Emily and three times as many as Bob bought. If Emily bought 6 candies, how many candies did Bob buy?
[Answer]: Jennifer bought twice as many as Emily (who bought 6 candies) which is 6 * 2 = 12 candies. 12 candies (that Jennifer bought) is three times as much as what Bob bought which means 3 * what Bob bought = 12. Dividing both sides of the equation by 3 gives: Number of candies Bob bought = 12 / 3 = 4 candies.
So the answer is 4.

[Question]: Donald drinks 3 more than twice the number of juice bottles Paul drinks in one day. If Paul drinks 3 bottles of juice per day, how many bottles does Donald drink per day?
[Answer]: Twice the number of bottles Paul drinks in one day is 3 * 2 = 6 bottles. So, the number of bottles that Donald drinks in one day is 6 + 3 = 9 bottles.
So the answer is 9.

[Question]: John sends his son to prep school. It cost $20,000 per semester. There are 2 semesters in the year. How much does it cost to send the kid to 13 years of school?
[Answer]:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
It cost 20000 * 2 = $40,000 a year. So it cost 40,000 * 13 = $520,000.
So the answer is 520000.