The task is to generate the correct answer for a given math problem.

Example Input: Problem: danny and steve are running towards each other , each one from his own house . danny can reach steve ' s house in 25 minutes of running , which is half the time it takes steve to reach danny ' s house . if the two started to run at the same time , how much time longer will it take steve to reach the halfway point between their houses than danny to reach the halfway point between their houses ?
Example Output: 12.5 minutes .

Example Input: Problem: a 270 metres long bullet train running at the speed of 120 kmph crosses another bullet train running in opposite direction at the speed of 80 kmph in 9 seconds . what is the length of the other bullet train ?
Example Output: 230

Example Input: Problem: the ratio of the volumes of two cubes is 1331 : 2197 . what is the ratio of their total surface areas ?
Example Output:
121 : 169