Percy wants to save up for a new PlayStation, which costs $500. He gets $200 on his birthday and $150 at Christmas. To make the rest of the money, he's going to sell his old PlayStation games for $7.5 each. How many games does he need to sell to reach his goal? Give the rationale and then the answer.
Let's think step by step. He needs to earn $150 more dollars because 500 - 200 - 150 = 150. He needs to sell 20 games because 150 / 7.5 = 20.. The answer is: 20.

A teacher asked Adelaide, Ephraim, and Kolton to buy ducks and monitor their growth patterns and features for their science class. Adelaide bought twice the number of ducks that Ephraim bought, while Ephraim bought 45 fewer ducks than Kolton. If Adelaide bought 30 ducks, what's the average number of ducks the three bought? Give the rationale and then the answer.
Let's think step by step. If Adelaide bought 30 ducks, Ephraim bought 30 ducks / 2 = 15 ducks. Since Ephraim bought 45 fewer ducks than Kolton, Kolton bought 45 ducks + 15 ducks = 60 ducks. The total number of ducks the three bought is 60 ducks + 15 ducks + 30 ducks = 105 ducks. The average number of ducks each bought is 105 ducks / 3 people = 35 ducks / person.. The answer is: 35.

Cooper is building a brick fence around all four sides of his property. Each of the four walls of his fence is 20 bricks long, 5 bricks high, and 2 bricks deep. How many bricks does Cooper need to complete his fence? Give the rationale and then the answer.
Let's think step by step. A single layer of each wall requires 5 rows * 20 bricks per row = 100 bricks. As each wall has a thickness of 2 bricks, he will need 100 bricks * 2 = 200 bricks per wall. If the complete fence contains four walls, he will require a total of 200 * 4 = 800 bricks.. The answer is: 800.