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

Example Input: Problem: in a certain country 1 / 5 of 8 = 4 . assuming the same proportion , what would be the value of 1 / 4 of 16 ?
Example Output: 10

Example Input: Problem: a train running at the speed of 72 km / hr crosses a pole in 9 seconds . find the length of the train .
Example Output: 180 meter

Example Input: Problem: if x and y are integers and 2 x y = 11 , then 4 x + y can not be
Example Output:
17