In a certain code, ZINC is written as XMRA. How is IRON written in that code?

Explanation

1. 01

   No single shift turns ZINC into XMRA. Reverse ZINC to get CNIZ.

2. 02

   CNIZ to XMRA: C (3) to X (24), N (14) to M (13), I (9) to R (18), Z (26) to A (1). Each pair adds to 27, so these are opposite letters.

3. 03

   IRON reversed is NORI; opposites of N, O, R, I are M, L, I, R.

4. 04

   The code is MLIR.