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

Example Input: Problem: 13 buckets of water fill a tank when the capacity of each bucket is 42 litres . how many buckets will be needed to fill the same tank , if the capacity of each bucket is 6 litres ?
Example Output: 91

Example Input: Problem: zachary is helping his younger brother , sterling , learn his multiplication tables . for every question that sterling answers correctly , zachary gives him 3 pieces of candy . for every question that sterling answers incorrectly , zachary takes away two pieces of candy . after 6 questions , if sterling had answered 2 more questions correctly , he would have earned 31 pieces of candy . how many of the 6 questions did zachary answer correctly ?
Example Output: 7

Example Input: Problem: the length of a rectangle is reduced by 22 % . by what % would the width have to be increased to maintain the original area ?
Example Output:
28 %