Which organelle is known as the powerhouse of the cell?

If 7@8 = 15, 3@5 = 8, 9@2 = 11, then 4@6 = ?

What comes next: 3, 7, 13, 21, 31, ?

In a code, if CAT equals 3 times 1 times 20 equals 60, then DOG equals?

A is B\'s father. D is A\'s wife. C is D\'s only child. How is B related to C?

Statements: No table is a chair. Some chairs are stools. All stools are benches. Some benches are beds. Conclusion I: No table is a bench. Conclusion II: Some chairs are beds. Which is correct?