Step-by-step explanation:
You will use combinations
20C3 = 20*19*18= 6840 there are 6840 combinations that are possible. You can look up to find a combination calculator. For combinations the order does not matter, this order does not matter. For permutations order does matter.
Answer:
4c^3+8c^2-9c-18
It’s the first one on the top left corner
