[Question]Kris is blowing u balloons for her sister's party. She has 30 minutes to blow up as many balloons as possible and decides to enlist her brother's help to increase the number of balloons. Kris can blow up a total of 2 balloon per minute, and her brother works twice as fast. After 15 minutes, her brother doubles his speed and works at this new speed for the remaining 15 minutes. After the 30 minutes, how many balloons, in total, did Kris and her brother blow up?
[Answer]Throughout the 30 minutes, Kris blows up 2 balloons per minute * 30 minutes = 60 balloons. Her brother works at double Kris' speed in the first 15 minutes so he works at 2 balloons per minute * 2 = 4 balloons per minute. So in the first 15 minutes, he blows up 4 balloons per minute * 15 minutes = 60 balloons. In the second 15 minutes, he is working at double the rate he did previously, so he blows up 4 balloons per minute * 2 = 8 balloons per minute. In the second 15 minutes, Kris' brother therefore blows up 8 balloons per minute * 15 minutes = 120 balloons. Throughout the 30 minutes, he has blown up a total of 60 + 120 = 180 balloons. Kris and her brother therefore blew up a total of 60 balloons from Kris + 180 balloons from Kris' brother = 240 balloons. The answer is 240.

[Question]A pencil costs $0.5 each and a folder costs $0.9 each. An office needs two dozen pencils and 20 pieces of folders. How much does it cost to buy the office supplies?
[Answer]Two dozens of pencils are equal to 2 x 12 = 24 pencils. So the total cost of pencils is $0.5 x 24 = $12. The total cost of folders is $0.9 x 20 = $18. Thus, the cost to buy the office supplies is $12 + $18 = $30. The answer is 30.

[Question]Jason has a carriage house that he rents out. He's charging $50.00 per day or $500.00 for 14 days. Eric wants to rent the house for 20 days. How much will it cost him?
[Answer]He wants to rent for 20 days and there is a deal if you rent for 14 days so that leaves 20 - 14 = 6 individual days. Each individual day is $50.00 and he will have 6 individual days for a total of 50 * 6 = $300.00. 14 days costs $500.00 and 6 days costs $300.00 for a total of 500 + 300 = $800.00. The answer is 800.

[Question]Joan has 2 hours to get all her music practice done. She spends 30 minutes on the piano, 25 minutes writing music on her computer, and 38 minutes reading about the history of the piano. Her final work is to use a special finger exerciser. How much time does she have left to use this?
[Answer]
She has 120 minutes to practice because 2 x 60 = 120. She has already spent 93 minutes on her work because 30 + 25 + 38 = 93. She has 27 minutes to use on finger exercise because 120 - 93 = 27. The answer is 27.