Most manufacturers fixer capacity is stated in how many 35mm rolls of film can be fixed per volume. If you are developing 8x10 sheet film and the manufacturer states that 1 liter of fixer is good for 15 rolls of 35mm, how many sheets of 8x10 film could you assume the fixer is capable of fixing before nearing exhaustion? What is the film surface correlation between 35mm and 8x10?