Which explanation could be used to verify weather the functions are inverse

Astore has clearance items that have been marked down by 60%. they are having a sale, advertising an additional 55% off clearance items. what percent of the original price do you end up paying?

Ellen makes and sells bookmarks. she graphs the number of bookmarks sold compared to the total money earned. why is the rate of change for the function graphed to the left?

The volume of a box varies directly with its length if a box in the group has a length of 30inches and k=24 what is its volume