answer:We can find the prime factorizations of each number: 3=3 4=2^2 6=2cdot3 15=3cdot5 To find the least common multiple, we take the highest power of each prime that appears in any of the factorizations. The highest power of 2 is 2^2, the highest power of 3 is 3, and the highest power of 5 is 5. Therefore, the least common multiple is 2^2cdot3cdot5=boxed{60}. The answer is: 60

answer:The zoo has 21 penguins. It also has twice as many polar bears as penguins, so it has 21 x 2 = 42 polar bears. Therefore, the zoo has a total of 21 + 42 = 63 animals. 63 The answer is: 63

answer:Bob has double the number of sheep as Mary, so he has 2 * 300 = 600 sheep. In addition, Bob has 35 more sheep than Mary, so he has a total of 600 + 35 = 635 sheep. Mary needs to have 69 fewer sheep than Bob, so she needs to have 635 - 69 = 566 sheep. Mary currently has 300 sheep, so she needs to purchase 566 - 300 = 266 sheep. Therefore, Mary needs to purchase 266 sheep in order to have 69 fewer sheep than Bob. 266 The answer is: 266

answer:2/5 of 20 cookies is equal to (2/5) x 20 = 8 cookies. Therefore, Neil gave 8 cookies to his friend. The number of cookies left for Neil is 20 - 8 = 12 12 The answer is: 12