For future reference use ^ to show exponents, example: 4^2 to show 4 to the second power.
-3p^3 + 5p + (-2p^2) + (-4) - 12p + 5 - (-8p^3)
first we are going to fix all of the addition and subtraction signs remember negatives cancels out negatives, and negatives with positives make negatives.
5p^3 -2p^2 -7p +1
Onces you add like terms you pretty much simplified it.
Final answer: 5p^3 -2p^2 -7p +1