What’s the answer please help

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5

Which questions would most a reader identify the author's purpose for writing? check all that apply. what type of text is this? what type of reviews did the book receive? how many copies of the book have been sold? what is the central idea? how does this text make one feel?