How many permutations of the letters a, b, c, d, e, f, g have either two or three letters between a and b? My guess for this is that if a and b have to have two letters between them, then there are 5! ways to arrange the rest of the letters, right? Same deal if a and b have to have three letters between them. So: 5! + 5! Would be my answer. Am I anywhere close with this one? Thank you.