
It's easier than it looks on the surface.
Let's call Kp = 3.5 x 10^4 the original Kp. The second equation is just 1/2 of the first one; therefore, new Kp = (original Kp)^{1/2}.
If you had 2N2 + 6H2 <==> 4NH3, then
new Kp = (original Kp)^{2} . In other words, just raise the original Kp to whatever power the new equation is relative to the original coefficients. In these two examples, that is 1/2 and 2.

where does the temperature factor in? I raised it to 1/2 and got 1.75, but that was not the right answer.
(I forgot to mention this, but the first reaction is the original one)
Could you put a example up? I am very much a visual learner and need to see it before I can do it.

As long as the temperature doesn't change, K doesn't change. So for 1/2 the reactants then the new Kp = 3.5 x 10^4)^{1/2.
How did you get 1.75? I'm not surprised the key told you that was wrong.
I have square root of 3.5 x 10^4 = 187 and not 1.75.
Let me know if still have problems. (I just see how you got that number. You divided 3.5/2 = 1.75. You forgot the exponent of 10^4 I think.)}

Is there a good website that has good examples for ap chemistry ranging from easy to difficult?

Here is one that I use often to direct students. Its' written very well and it's an AP site.
(Broken Link Removed)

calculate the standard enthalpy change for each of the following reactions. N2O4(g)+4H2(g)=N2(g)+4H2O(g)