algebraic fractions

good question......

Unsure of the question
If what you want is

(3xyz^2) (2y)
-----------------
(6y^4) (xz^4)

Then you can cancel out the following.
2x3 from the top and 6 from the bottom
z^2 from the top and bottom leaving z^2 in the bottom
y^2 from the top and bottom leaving y^2 in the bottom (see the two y's?)
x from the top and bottom eliminating all x's

I leave it to you to finish.