Chemistry
posted by Savannah .
Calculate Kc.
CH_4(g) + H_2O(g) <> CO(g) + 3H_2(g)
Kp= 7.7 x 10^24 at 298K.
Should I use the formula Kp= Kc(RT)^Deltang
If so I have no idea where to start.

What do you mean you don't know where to start. This is just a case of substitute and solve.
7.7E24 = Kc(0.08205*298)^(42)
Solve for Kc.