Question 1: The average of 10 numbers is -5. A new number is added to the list making the average -6. What is the new number?
To solve this question, first note that the sum of these numbers is -5*10 = -50. If the average of 11 numbers is -6, we must have that they add up to -6*11=-66. Therefore, the new number is -66-(-50) = -66+50 = -16.
Question 2: It is hard to explain why, but just know that the answer is No Solution. I think you must have made a typo, like maybe the product is -24?