You coordinate volunteers for litter cleanup in local parks. Your spreadsheet lists drivers
and the number of seat belts in each driver's car. The spreadsheet calculates the number of
drivers (D) and the total number of seat belts (S). You want to know the maximum number of
volunteers, besides drivers, that can be transported to the park in a single trip given that
each person must have a seat belt of their own. Which of the following formulas would give
your result?