Hard
If MOBILE is written as LNAHKD, then PHONE will be written as -
Explanation
Explanation
Each letter in MOBILE is shifted back by 1 to get LNAHKD (M->L, O->N, B->A, I->H, L->K, E->D). Applying the same -1 shift to PHONE: P->O, H->G, O->N, N->M, E->D, giving OGNMD.
PRO TIP
Re-check your working by substituting the answer back into the original question.