Answer this question:Buoys are placed in the ocean at even intervals away from the beach to help swimmers monitor how far away from the beach they have swum. If a swimmer reaches the third buoy, they have swum out 72 meters. How many meters from the beach is the fourth buoy?
The buoys are evenly spaced, so the first buoy is 72 / 3 = 24 meters from the beach. Thus, the fourth buoy is 24 * 4 = 96 meters from the beach.
The answer is 96.

Answer this question:A store is selling mobile phones. This store contains 20 units of phones but the owner found out that there were 5 defective units. After he got rid of the defective units, he started to sell the rest of his units to customer A who bought 3 units, customer B who bought a certain amount of units, and customer C who bought 7 units. In the end, all non-defective units were sold. How many units were sold to Customer B?
There were 20 - 5 = 15 units of non - defective smartphones. There were 3 + 7 = 10 units sold to customers A and C. So, 15 - 10 = 5 units were sold to customer B.
The answer is 5.

Answer this question:A soccer ball takes twenty minutes to inflate. Alexia and Ermias are inflating balls, with Alexia inflating 20 balls and Ermias inflating 5 more balls than Alexia. Calculate the total time in minutes they took to inflate all the soccer balls.
To inflate a soccer ball, it takes 20 minutes, and if Alexia inflated 20 soccer balls, she took 20 * 20 = 400 minutes. Ermias has 5 more soccer balls than Alexia, meaning she has a total of 20 + 5 = 25 soccer balls. If each soccer ball takes 20 minutes to inflate, Ermias took 25 * 20 = 500 minutes to inflate all the soccer balls she had. Alexia and Ermias took 400 + 500 = 900 minutes to inflate all the soccer balls.
The answer is 900.

Answer this question:Colbert is building a treehouse out of wooden planks. The treehouse needs 200 wooden planks. A quarter of these planks come from Colbert’s storage, half of these planks come from Colbert’s parents, 20 planks come from Colbert’s friends and he buys the rest from the store. How many planks of wood does he need to buy from the store to finish his treehouse?

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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In Colbert’s storage, there are 200 wooden planks / 4 = 50 wooden planks. From his parents, there are 200 wooden planks / 2 = 100 wooden planks. So in total, Colbert has not had to buy 50 wooden planks from storage + 100 wooden planks from his parents + 20 wooden planks from his friends = 170 wooden planks. He therefore still needs to buy 200 needed wooden planks – 170 owned wooden planks = 30 wooden planks.
The answer is 30.