Answer: D

Don't overthink this one. To solve for 4x + 18, all we need is the value of x. Both statements give us an equation that allows us to solve for x. Thus, both statements are sufficient independent of each other, and choice (D) is correct.

It may be tempting to recognize that 2x + 9, in statement (1) is half 4x + 18, so there is a quick way to solve for 4x + 18. This is true, but don't let it make the question too complicated. There is no reason to solve, and if you are thinking along these lines, you might notice that (2) cannot be solved this way, and make the mistake that (2) is thus not sufficient. It is, and it can be recognized as such very quickly.