If you have time, these kinds of questions are very similar to the logical reasoning questions on the lsat. There is a book called "Logical Reasoning Bible" which will teach you how to do these problems very easily. I'll explain the techniques used in the book on this problem.
You have 5 choices R,S,T,U,W
so draw 5 places
_ _ _ _ _ _
Now the prompt says the R comes immediately before S so that is a block. It also says U comes before T with at least one space in between. Finally, W cannot be last.
RS < draw a square around this to show it is a block
U_T < draw this in a way that represents there is AT LEAST one space between the 2 and put a square around it since it is also a kind of block
_ _ _ _ _ _ < this shows that W cannot be last
***********
W (*s are just empty space, you don't need to draw them)
Now you can see the block RS must slide between the 5, making S impossible for the first and R for the last. You can draw a slash in the 1st & 2nd spots for S and R if you want, or just remember it. Also, U and T cannot be last/2nd to last or first/2nd, respectively. Now you have 2 answers for what can't be 2nd (U and S).
_ _ _ _ _
S*
T***
U*
RT********
UAs far as the 3rd, if you play around with the variables you'll see that W cannot be center because it block U_T and RS. (If you put RS first then W, U and T will not have a space).
Again, if you have time that Logical Reasoning bible is very helpful and will also teach you some logic. Good luck with whatever you choose!!!!