[Question]Jeremy buys 30 watermelons. He eats 3 watermelons per week. Each week he gives 2 to his dad. How many weeks will the watermelons last?
[Answer]Jeremey goes through 3 + 2 = 5 watermelons per week. Therefore, the watermelons will last him to 30 / 5 = 6 weeks. The answer is 6.
Q: Ryan has 40 balls. There are twice as many red balls as blue while the rest are green. If there are 11 blue balls, how many green balls are there?
A: There are 11 blue x 2 red / blue = 22 red balls. The total number of blue and red balls is 11 blue + 22 red = 33 balls. There are 40 balls - 33 balls = 7 green balls. The answer is 7.
Question: John commissions an artist to make him a 9 by 13 drawing. A black and white drawing that size would cost $160. He wants a color drawing so that is 50% more expensive. How much did he pay?
Answer: The extra cost for coloring is 160 * .5 = $80. So the total cost was 160 + 80 = $240. The answer is 240.
[Question]In ten years, I'll be twice my brother's age. The sum of our ages will then be 45 years old. How old am I now?
[Answer]Let X be my age now. In ten years, I'll be X + 10 years old. In ten years, my brother will be (X + 10) * 1 / 2 years old. In ten years, (X + 10) + (X + 10) * 1 / 2 = 45. So (X + 10) * 3 / 2 = 45. X + 10 = 45 * 2 / 3 = 30. X = 30 - 10 = 20 years old. The answer is 20.
Q: Gracie was 7 inches shorter than Grayson. Grayson was 2 inches taller than Griffin. Griffin is 61 inches tall. How many inches tall is Gracie?
A: Grayson = 61 + 2 = 63 inches. Gracie = 63 - 7 = 56 inches. Gracie is 56 inches tall. The answer is 56.
Question: Tracy set up a booth at an art fair. 20 people came to look at her art. Four of those customers bought two paintings each. The next 12 of those customers bought one painting each. The last 4 customers bought four paintings each. How many paintings did Tracy sell at the art fair?
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.
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The first 4 customers bought 4 * 2 = 8 paintings. The next 12 customers bought 12 * 1 = 12 paintings. The last 4 customers bought 4 * 4 = 16 paintings. In total Tracy sold 8 + 12 + 16 = 36 paintings. The answer is 36.