Cody wants to watch a new movie that is 3 hours long. he has watched 1/6 of the movie so far. what fraction of one hour did cody spend watching the new movie?

What we know: 
1/6 = what Cody wathed
1 stands for the unit that cody has watched a move (minutes) 
6 = stands for the entire length of the movie (minutes)

Tharefore: If 6 stands for the entire length of the movie the movie is equal to 3 hours. However we are giving the unit in minutes not in hours, it would be:
3 x 60 = 3 stands for the ours 60 stands for minutes in an hour. That equals to 180.
This means that the 6 = 100% = 180min of the movie.

To figure what 1 stands for we need to divide 1/6. That will equal to 0.1(6). 0.1(6) x 180 (minutes of the entire movie) = 30 which would be the answer. Here is what you should have done using mathematical communication:

converting 3 h to minutes:

3 x 60 = 180 minutes
180 = the length of the entire movie
1/6 = 0.1(6)
0.1(6) x 180 = 30 
... 30 /180 is the fraction of minutes that Cody spend watching the movie
in other words Cody just spent 30 min watching the movie.

The correct answer is $90