How to evaluate if Big-Theta and Big-Omega of two functions are equal?

Question

I have an assignment that is to prove if these are True or False:

• a) 150n^3 + 43n^2 + 50^n + 3 = Ω(n^5)
• b) n^10 + 30n^8 + 80n^6 = O(n^12)
• c) 55n