Definition: 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.
Input: Context: 22 children were riding on the bus. At the bus stop 40 children got on the bus while some got off the bus. Then there were 2 children altogether on the bus. 

 Question: How many children got off the bus at the bus stop?

60