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.

simon mark kevin and carl love collecting stamps . they meet up every month to compare and share their collections with each other . during the previous month kevin was able to collect 45 stamps while simon was only able to collect 27 how many more stamps does kevin have more than simon ?
18