The College of Veterinary Medicine at Texas A&M University conducted a study of the rattlesnake vaccine for dogs. The researchers determined that:
•12 out of 15 cases of dogs that received the vaccine prior to the rattlesnake bite survived, and
•8 out of 18 cases of dogs who did not receive the vaccine prior to the rattlesnake bite survived.
If there were 900 dogs in the study that received the vaccine and were then bitten by a rattlesnake, how many of this group did NOT survive the rattlesnake bite?