You have to answer

Question

2
essay questions for an exam. There are
8
essays to choose from. How many different groups of
2
essays could you possibly choose?

Answer 1

Let's number each essay, 1 - 8

1, 2; 1,3; 1,4; 1,5; 1,6; 1,7;, 1,8 >> 8
2,3; 2,4; 2,5; 2,6, 2,7; 2,8 >> 6

Keep going.

Answer 2

There are 8 ways to choose the 1st question.
Now that that one's taken, there are 7 ways to choose the 2nd one.
So, ...

Answer 3

21