Let us have the rule:

p(X,Y) :- 	D is Y div X,
		Y is D * X.


What will the Prolog interpreter answer to the following queries:
a)	p(7,21).
b)	p(3,10).
c)	p(6,30).
d)	p(6,35).
e)	p(X,21).
f)	Can you simplify the above rule?