I need to be able to see the question for me to answer. Unless you mean like, what you actually are. I would think you're subtracting numbers. :/
Given expression:
.
First we would apply exponents of exponent rule on the top.

Therefore,

=
Applying quotient rule of exponents.


= 
<h3>Therefore,

is the simplified form of the expression

</h3>
D is the right answer, you got it right
No, 43 is a prime number, so that statement is false.