There are four seats in a row at a concert. phillip will sit next to sally, but will not sit next to gerald. gerald will not sit next to john. who is sitting next to john?

My best answer would be Phillip. 

So there are four seats, two seats in the middle. Sally has to be in the middle because she is sitting next to Phillip. Phillip is also in the middle, and since he is not sitting next to Gerald that means John is the only other person (besides Sally) who is sitting next to him. Leaving both Gerald and John on opposite ends of the four seats.

I hope this helps and/or makes sense. 

Lets say p=philip and s=sally and g=gerald and j=john

ps and sp is allowed but not pg or gp

gj and jg is not allowed

maybe like this:

jpsg

so philip is definitly sitting next to john