IE : RV : : KC :?

IE : RV
I is 9th Letter from left, R is 9th Letter from right, similarly E is 5 th Letter from Left, V is 5 th letter from the right in the first pair.
KC : PX
K is 11 th letter from left, P is 11 th letter from right and C is 3 rd letter from left, X is 3rd letter from right.