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.

[Q]: Context: Winter is almost here and most animals are migrating to warmer countries. There are 8 bird families living near the mountain. If 42 bird families flew away to africa and 31 bird families flew away to asia 

 Question: How many more bird families flew away to africa than those that flew away to asia?
[A]: 11


[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


[Q]: Context: The Razorback shop makes $ 192 dollars off each t-shirt and $ 34 off each jersey. During the Arkansas and Texas tech game they sold 157 t-shirts and 19 jerseys. 

 Question: How much more does a t-shirt cost than a jersey?
[A]:
158