Three-activities implementable in parallel, have the following time-cost relationship for direct cost component in each, Activity A: 10 days-800 units; 9 days-900 units; 8 days-1000 units, Activity B: 11 days-1200 units; 10 days-1350 units; 9 days-1500 units, Activity C: 7 days-500 units; 6 days-700 days; 5 days-900 units, The feasible range of total direct cost component for the three activities together is