Query about Question 2 from "PrepSwift: # of Integers in Interval" [3668]

https://prepswift.gregmat.com/quizzes/quiz/prepswift-of-integers-in-interval (Question 2)


The video explanation said for “exclusive” its number before last in a range subtracted by number before first in a range, + one. However the prepswift solution gives a completely different formula (& thus different exercise). So which is the correct rule for exclusive? This is confusing.

Same thing - you can show that the two are equivalent.