On a particular week, Fatima's restaurant served 25 people food and drinks, and 3/5 of that number came to buy coffee. How many people did not buy coffee in the restaurant?
Think hard. Detailed solution:
10
The number of customers who were served coffee in the restaurant is 3 / 5 * 25 = 15.

If the total number of customers who came to the restaurant was 25, then 25 - 15 = 10 customers did not buy coffee.

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So, the answer is 10