Q: A school library has 120 books. Each student needs 5 books for their classes. The library was able to help 4 students on the first day of school, 5 students on the second day and 6 students on the third day. How many students can the library help out on the fourth day of school?
A: 9
Step-by-step reasoning process: On the first day, the library used 4 students * 5 books = 20 books. On the second day, the library used 5 students * 5 books = 25 books. On the third day, the library used 6 students * 5 books = 30 books. On the fourth day, the library had 120 books - 20 - 25 - 30 = 45 books remaining. The library can help 45 books / 5 books = 9 students on the fourth day.

Q: Elmer has a pond that initially contained 2400 pollywogs, but these pollywogs matured into toads and left the pond at a constant rate of 50 pollywogs per day. In addition, Elmer has a son named Melvin, who loves to catch pollywogs, remove them from the pond, and release them into a nearby stream. For the first 20 days, Melvin caught 10 pollywogs per day and released them into the stream. How many days did it take for all of the pollywogs to disappear from the pond?
A: 44
Step-by-step reasoning process: For the first 20 days, the combined rate of disappearance of pollywogs from the pond is 50 + 10 = 60 pollywogs per day. During these first 20 days, the total number of pollywogs removed was 60 * 20 = 1200 pollywogs. This means after 20 days there were 2400 - 1200 = 1200 pollywogs left in the pond. At a disappearance rate of rate 50 pollywogs per day, it will take an additional 1200 / 50 = 24 days for the rest of the pollywogs to disappear from the pond. Thus, overall, it will take 20 + 24 = 44 days for all of the pollywogs to disappear from the pond.

Q: Mr. Llesis had 50 kilograms of rice. He kept 7/10 of it in storage and gave the rest to Mr. Everest. How many kilograms of rice did Mr. Llesis keep than Mr. Everest?
A: 20
Step-by-step reasoning process: Mr. Llesis kept 50 x 7 / 10 = 35 kilograms of rice. So, he gave 50 - 35 = 15 kilograms of rice to Mr. Everest. Therefore, Mr. Llesis kept 35 - 15 = 20 kilograms more than Mr. Everest.

Q: Police officer A patrols 36 streets in 4 hours. His colleague, officer B, patrols 55 streets in 5 hours. How many streets will both officers patrol in one hour?
A: 20
Step-by-step reasoning process: Officer A patrols 36 streets / 4 hours = 9 streets / hour. Officer B patrols 55 streets / 5 hours = 11 streets / hour. Together officer A and B patrol 9 streets / hour + 11 streets / hour = 20 streets / hour.