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: 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

Example Input: Context: At the arcade Dave had won 13 tickets. If he used 8 to buy some toys and 18 more to buy some clothes 

 Question: How many more tickets did Dave use to buy clothes than he did to buy toys?
Example Output: 10

Example Input: Context: Marco and his dad went strawberry picking. Marco's strawberries weighed 15 pounds. If together their strawberries weighed 37 pounds. 

 Question: How much did his dad's strawberries weigh?
Example Output:
22