Ok, so what you want to do is begin with parentheses, and multipl the positive sign (which is 1, because if there is no number there, it will always be one, whether it is negative or positive) and your equation will now be:
4p + 9 - 7p + 2. Next, you will want to simplify, or combine like terms. And you know, you now have 4p, -7p, +9, and +2. So, add together the 9 and 2 to get 11, and you subtract 7p from 4p to get -3p. So, your final answer will be C, -3p + 11.
