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.
One example: Context: Sam is 6 feet tall and Alex is 5 feet tall 

 Question: By how many feet is Sam taller than Alex? 
Solution is here: 1
Explanation:  Sam's height - Alex's height = 6-5 = 1

Now, solve this: Context: Bobby ate 23 pieces of candy. If he initially had 30 pieces of candy 

 Question: How many pieces of candy does he still have left?
Solution:
7