[Question]: A small zoo houses a variety of 68 wild animals. After they send a gorilla family of six to a different zoo, they adopt a hippopotamus from another zoo. A while later, an animal rescue contacted them, and the zoo took in three endangered rhinos. Then one of their lionesses gave birth to cubs, and they opened a meerkat exhibit with twice as many meerkats as they had gained lion cubs. The zoo then had 90 animals in all. How many lion cubs were born at the zoo?
[Answer]: Let C be the number of lion cubs. There are 2C meerkats in the new exhibit. The zoo sent 4 gorillas away, so they had 68 - 6 = 62 animals left. They adopted a hippopotamus, so they had 62 + 1 = 63 animals. They took in 3 rhinos, so they had 63 + 3 = 66 animals. Thus, they had 90 - 66 = 24 new lion cubs and meerkats. Therefore, they had C + 2C = 3C = 24 new lion cubs as meerkats. Hence, there were C = 24 / 3 = 8 lion cubs born.
So the answer is 8.

[Question]: Shara collects shells. She had 20 shells before she went on vacation. On vacation, she found 5 shells per day for 3 days. Then he found 6 shells on the fourth day. How many shells does she have now?
[Answer]: Shara collected 5 x 3 = 15 shells for 3 days. So she collected 15 + 6 = 21 shells rom her vacation. Thus, she now has a total of 20 + 21 = 41 shells.
So the answer is 41.

[Question]: Bill is trying to control the pests in his garden. Each spider he introduces eats 7 bugs, and each time he sprays the garden he reduces the total bug population to 80% of what it was previously. If the garden has 400 bugs to start, and Bill sprays once and introduces 12 spiders, how many bugs are left?
[Answer]:
First find the total bug population after spraying: 80% * 400 bugs = 320 bugs. Then find the total number of bugs each spider eats: 12 spiders * 7 bugs / spider = 84 bugs. Then subtract that number from the number of bugs left after spraying to find final number of bugs: 320 bugs - 84 bugs = 236 bugs.
So the answer is 236.