At the start of the month the value of investment was $48.45 by the end of the month the value of interest changed by loss of $13.80 what was the value in dollars of the investment at the end of the month

Randy and trey take turns cleaning offices on the weekends. it takes randy at most 4 hours to clean the offices. it takes trey at most 6 hours to clean the offices. what is the greatest amount of time it would take them to clean the offices together? 2.4 hours 2.5 hours