Absolutely correct . . . good work!
It comes out that 3 and -6 are indeed the correct answers.
when you divide the given terms by (x+3), the remainder is 0 in both the cases.
when you divide the given terms by (x-6), you remainder in both the cases is 180
But if you divide the given terms by (x-3), the remainders are not the same..
You can check back by dividing the terms by (x+3), (x-6), and (x-3), and you'll see 3 and -6 are the correct values for p...