What was the question for this implicit rationale, and corresponding answer?
First, add the number of kosher meals to the number of vegan meals: 7 meals + 8 meals = 15 meals. Then subtract the three meals that are both kosher and vegan since they got counted twice: 15 meals - 3 meals = 12 meals. Finally, subtract that number from the total number of meals to find the number of meals that are neither kosher nor vegan: 30 meals - 12 meals = 18 meals.
 The answer: 18
The question: Megan is delivering meals on wheels. Out of her 30 clients, 7 need vegan meals, 8 need kosher meals, and three people need meals that are both vegan and kosher. How many meals does Megan deliver that are neither kosher nor vegan?