You are given a math word problem and you are supposed to only use subtraction on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

Example Input: Context: A book has 2 chapters across 81 pages. The second chapter is 68 pages long. 

 Question: How many pages are in the second chapter?
Example Output: 13

Example Input: Context: Next on his checklist is wax to stick the feathers together and colors to paint them. He needs a total of 57 g of colors to paint them. He needs 22 g of wax more. If the feathers require a total of 353 g of wax 

 Question: How many grams of wax does he already have?
Example Output: 331

Example Input: Context: 23 children were riding on the bus. At the bus stop 24 children got on the bus while some got off the bus. Then there were 8 children altogether on the bus. 

 Question: How many more children got off the bus than those that got on?
Example Output:
15