Four plumbers each charge a flat fee plus an hourly rate for repair visits. the table shows their total costs for repairs that required various amounts of time. total cost of repairs hours needed for repair cost for plumber a cost for plumber b cost for plumber c cost for plumber d 1 $35 $55 $50 $50 2 $65 $75 $75 $60 3 $95 $95 $100 $70 which plumber charges the greatest hourly rate? plumber a plumber b plumber c plumber d