The tub of a washer goes into its spin-dry cycle, starting from rest and reaching an angular speed of 2.4 rev/s in 10.9 s. At this point the person doing the laundry opens the lid, and a safety switch turns off the washer. The tub slows to rest in 19.1 s. During the whole process of starting up and stopping, through how many revolutions does the tub turn? Assume constant angular acceleration while it is starting and stopping.