you asked me about how did i came up with my answer this is what i did:

Write each fraction in simplest form.

#18

(-5x^3y^3)/(-20xy^4)

= (3X(-5)X(x)X(x)X(x)X(y)X(y)X(y))/(2X2X(-5)X(x)X(y)X(y)X(y)X(y))

= after canceling the common terms top and bottom i am left with

= 3 and 2 OF x on top
and 4 and one y on the bottom

thats how i came about my answer.

my answer is: (3x^2)/(4y)

um...can you help me with my math please...?

Here's how I would simplify this one:

-5x^3y^3
--------
-20xy^4

-5/-20 reduces to 1/4; the rest looks OK from what you have done.

Therefore, you end up with this:

x^2
---
4y

I hope this is clear and will help.