20 of 140 seventh grade students 15% earn the presidential physical fitness award. how many students earned the award

You divide 140/20 then multiply by 3 to get the answer of 21 total students. 

It is useful for historians to write narratives so that history can be passed on from their point of view.  think about a story being told in third person, then think about it again being told in first person, by someone who actually experienced the event.