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: Edward spent $ 16 to buy books and $ 8 to buy pens. Now he has $ 19. 

 Question: How much more did Edward spend on books than pens?
Example Output: 8

Example Input: Context: Dave had 19 apps on his phone. He deleted 5 apps. 

 Question: How many apps are left on his phone?
Example Output: 14

Example Input: Context: Ed had 6 more marbles than Doug. Doug lost 7 of his marbles at the playground. If Ed had 22 marbles 

 Question: How many marbles does Doug have now?
Example Output:
9