Mark uses 1 pt 9 fl oz and then 2 pt 10 fl oz from a container of film
developer that holds 3 qt. How much of the developer remains?
How would I set this problem up?
Find out how many pints are in 3 qts.
Find out how many oz are in a pint.
Then you can figure out how much was used and, as a result, how much was left.