Find how many different groups of 2 elements, with repetition, can be formed

Question

with the letters: a, b, c, d.

Answer 1

I solved it like this: 5!/2!*2!=10, but im not sure

Answer 2

It said you can use repetition, so

first position: 4 ways
second position : still 4 ways

so number of cases = 4*4 = 16