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1. There are 30 children in a school class.17 of them like the colour yellow. 13 of them like the colour red. 8 of them like both yellow and red. How many like neither yellow or red?
0
8
4
9
2. There are 30 children in a school class. 22 of them like yellow or red. 15 of them like yellow. 15 of them like red. How many like both red and yellow?
8
7
15
22
3. There are 100 wizards in Slytherin. 38 of them play quidditch, 49 speak parseltongue and 15 of them are in second year. 6 second years play quidditch, as do 8 parselmouths. Also, 2 second years are parselmouths. Surprisngly, no-one falls under all three categories. How many don't play quidditch, are not in second year and can't speak to snakes?