I do not understand your first question. A print can be any size you wish and can be cropped to any ratio you desire. 'Standard' print sizes include 4" x 5", 4" x 6", 5" x 7", 6" x 9", 8" x 10", 11" x 14", 16" x 20", etc. I usually print full-frame 35mm negatives at 6" x 9", though for compositional purposes I may print to an entirely different size and ratio, such as 3" x 9.5" [6:19 ratio]. The ratio of a print size is simply the dimensions reduced to [or increased to] the smallest whole numbers. The ratio of an 8" x 10" print is 4:5.
35mm film ratio: a standard 35mm negative or slide measures 1" x 1.5". Doubling these numbers to eliminate decimals gives a ratio of 2:3.