First, add the number of kosher meals to the number of vegan meals: 7 meals + 8 meals = <<7+8=15>>15 meals
Then subtract the three meals that are both kosher and vegan since they got counted twice: 15 meals - 3 meals = <<15-3=12>>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 = <<30-12=18>>18 meals
#### 18