Simplify -3p3 5p (-2p2) (-4) - 12p 5 - (-8p3).

Well in order to simplify this you have to first do distributive property (this is when you multiply the outside number next to a parenthesis times the terms inside the parenthesis) when you do this you will get -3p3+5p+(4p2)-12p+40p3 see how there is still 1 parenthesis well lets do that one to finish with the distributive property -3p3+20p3-12p+40p3 now you have to add common like terms the only common like terms are -3p3, 20p3 and 40p3 so lets add or subtract those up to get 57p7, since -12p doesn't have any we leave it as it is... SO your last answer should be 57p3-12p

Hope this helps