In Sheldon most bicyclists aged 18 and over have lights on their bicycles, whereas most bicyclists under the age of 18 do not
It follows that in Sheldon most bicyclists who have lights on their bicycles are at least 18 years old
The Sheldon Library lent more books during the week after it began lending videos than it had in the entire preceding month. It follows that the availability of videos was responsible for the increase in the number of books lent.