A nail salon was completely booked at 2 pm for manicures. Each manicure costs $20.00 per client so the salon made $200.00. If there are 210 fingers in the salon at 2 pm, and everyone has 10 fingers, how many people in the salon are not clients? Let's think first. Chain of thought:
The salon made $200.00 and they charge $20.00 per client so there are 200 / 20 = 10 clients in the salon. There are 210 fingers in the salon and everyone has 10 fingers so there are 210 / 10 = 21 people in the salon. If there are 21 people in the salon and 10 are clients then there are 21 - 10 = 11 people in the salon that are not clients.
Therefore, the answer is 11.