Toby has 63 photos on his camera roll. He deletes seven bad shots, takes fifteen pictures of his cat, and then does a photo shoot with his friends. After editing the photos with his friends, he decides to delete three of them. His camera roll has 84 photos in the end. How many photos did Toby take in the photo shoot? Give me reasons, before answering the question
Let P be the number of photos in the photo shoot. After Toby deleted 7 shots, he had 63 - 7 = 56 photos. After taking 15 cat pictures, he had 56 + 15 = 71 photos. After the photo shoot, he had 71 + P photos. After deleting 3 photos, he had 71 + P - 3 = 68 + P photos. He had 68 + P = 84 photos in the end. Thus, Toby took P = 84 - 68 = 16 photos in the photo shoot. So the final answer is 16.