What expression is equivalent to 18c^8 d^9/9c^3 d^6

First, since all of the terms are multiplied, you can cancel them out to simplify them:

18/9 = 2

When a term has exponents on the top and bottom of a fraction, you subtract the bottom from the top:

c^8/c^3 = c^5

d^9/d^6 = d^3

So now, we can get rid of the fraction bar and put all of these terms into one expression:

2 (c^5) (d^3)