In the bedroom, there are 1 + 1 = <<1+1=2>>2 people in the house (Charlie and Susan).
Sarah and four friends then entered, a total of 4+1 = <<4+1=5>>5 people.
Together with Charlie and Susan, there are now 5+2 = <<5+2=7>>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 = <<8+7=15>>15
#### 15