it's been a while since I've done math, and i know most of this stuff but have some particular rust issues

such as:

in problems such as this one:

(x^2-3x-4) - (x^3+x^2+x+5)

what do I do? Obviously is not multiplying because of that - sign. do I have to solve the first one, which can be done easily, and then just substact the whole thing??

also in another problem I ended up with this:

9x^2-24x+16

I know I can contnue factoring but how exactly do I do it?

(3x- ) (3x+ )

Im not sure what to do when the x^2 has a number in front. do those 3 have to multiply the numbers I use in the blank space??

and this problem tells me to find the quotient and remainder

problem is: 4x^3-3x^3+x+1 divided by x+2

so my question is, how do I even start with this? do I literally divide it or does the x+2 flip to the top and I just multiply the rest??