You are given a math word problem and you are supposed to apply a single mathematical operator like addition, subtraction, multiplication, or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
Example: for a birthday party cody bought 30 regular sodas and 5 diet sodas . How many sodas are there ?
Example solution: 35
Example explanation: total sods = 30+5 = 35

Problem: the book fair sold 4 posters . now they have 2 posters left . how many posters did they have to begin with ?

Solution: 6