In a class, there are three types of students: those who play football, those who play basketball, and those who play both. If 10 students play football, 8 play basketball, and 3 play both, how many students play only football?
In a family of six members: A, B, C, D, E, and F, A is the father of B, C is the mother of B, D is the brother of B, E is the sister of B, and F is the grandfather of B. Who is the grandmother of B?
In a group of five friends: Alice, Bob, Charlie, David, and Eva, Alice is taller than Bob but shorter than Charlie. David is shorter than Eva but taller than Bob. Who is the tallest among them?