[Question]: Randy has $30. He spent $10 buying his lunch. He spent a quarter of the money he had left on an ice cream cone. What is the amount of money, in dollars, Randy has left?
[Answer]: Randy has 30 - 10 = 20 dollars left after buying lunch. Randy spent 20 / 4 = 5 dollars on the ice cream cone. Randy has 20 - 5 = 15 dollars left.
So the answer is 15.

[Question]: Flora has been experiencing frequent fractures. Dr. Juan has asked her to strengthen her bones by drinking 105 gallons of milk within 3 weeks. Flora thinks that drinking 3 gallons of milk daily will be enough, but her brother says she'll still need to drink more. To fulfill Dr. Juan’s requirement, how many more gallons must Flora drink daily?
[Answer]: 3 weeks translate to 3 * 7 days = 21 days. To meet Dr. Juan’s recommendation would mean drinking 105 / 21 = 5 gallons daily. This means that Flora must drink 5 - 3 = 2 more gallons daily.
So the answer is 2.

[Question]: A group of bedbugs infested an old mattress. Every day, the number of bedbugs would triple. After four days, there were 810 bedbugs burrowing into the mattress. How many bedbugs did the group start with?
[Answer]:
On the third day, there were one - third of the number of bedbugs as the fourth day, so there were 810 / 3 = 270 bedbugs. On the second day, there were one - third of the third day’s bedbugs, so there were 270 / 3 = 90 bedbugs. On the first day, there were 90 / 3 = 30 bedbugs in the group to start with.
So the answer is 30.