Verified Answer :

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