math
posted by fani .
An airplane left chicago O'Hare airport at 9:50 AM and arrived at Detroit,Michigan at 11:45 A.M.How long did the trip take?

11 45/609 50/60=
10 105/60 9 50/60
1hr 55min 
Ahh  but there's a time change involved. Chicago is in Central time and Detroit is in Eastern time. When it's 9:50 in Chicago, it's 10:50 in Detroit. The trip only took 55 minutes.