Find the quotient of and the remainder if it exists.
At a bake sale, Farida and Amira are selling slices of apple pie and lemon pie packaged together. They have 90 slices of apple pie and 80 slices of lemon pie, and they want to sell all the pie slices. What is the greatest number of packages they can put together? How many slices of each type of pie are in a single package?