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: 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

Example Input: Context: Dan has $ 7. He bought a candy bar for $ 2 and a chocolate for $ 3.

Question: How much money is left?
Example Output: 2

Example Input: Context: Dave had 24 apps and 9 files on his phone. After deleting some apps and files he had 5 files and 12 apps left.

Question: How many more apps than files does he have left on the phone?
Example Output:
7