What number minus 33 1/3% OF IT equals 30. 
I know the answer is 45,
but I do not know how to set up to get the answer. Please help!

Reason it out this way:
Suppose you knew the answer was X.  Then if you took 33 1/3 
percent of that X and then minused that off the X, you'd have 
to get 30, wouldn't you?

So take 33 1/3% of X.  That just means to take a third of X and
get X/3. Now minus that off the X.  To do that you just put down 
the X and then minus X/3 off of it, like this

     X - X/3

That would have to equal to 30. So put it equal to 30:

     X - X/3 = 30

Now solve that for X.  If you can't solve that, post again.

You'll get X = 45 when you solve it.

Edwin