In washing they are capable of making (1,200 x 60) / 6 = 12,000 units per hour. In filling they could make (700 x 60) / 3 = 14,000 units In capping they could make (250 x 60) / 1.5 = 10,000 units In Labelling they could make (450 x 60) / 2 = 13,500 units
The smallest is 10,000 units and it is therefore capping that is the bottleneck resource.
I don’t know why BPP has messed around with 12 units. It is not necessary and wastes time.