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: Sam is 6 feet tall and Alex is 5 feet tall

Question: By how many feet is Sam taller than Alex?
Example output: 1
Example explanation: Sam's height - Alex's height = 6-5 = 1
Q: 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?
A:
7