Original sentence: Bullet Nosed Betty is a nickname for the mountain type(4-8-2) steam engine series of locomotive.The mountain type locomotive was a step down in size from the much more prevalent Northern Type(4-8-4)
Edited sentence: Bullet Nosed Betty is a nickname for the mountain type (4-8-2) steam engine series of locomotive.The mountain type locomotive was a step down in size from the much more prevalent Northern Type (4-8-4)