While reading in bed with his wife Susan, Charlie heard a noise at the door. It was Sarah entering the bedroom with 4 friends. If there were also 8 people in the living room, how many people are in the house? Let's think first. Chain of thought:
In the bedroom, there are 1 + 1 = 2 people in the house (Charlie and Susan). Sarah and four friends then entered, a total of 4 + 1 = 5 people. Together with Charlie and Susan, there are now 5 + 2 = 7 people in the bedroom. Since there are 8 more people in the living room, the total number of people in the house is 8 + 7 = 15.
Therefore, the answer is 15.