In a certain code language, ‘3a, 2b, 7c’ means ‘Truth is Eternal’; ‘7c, 9a,…

In code-language elimination puzzles, comparing every pair of coded sentences that share codes and words lets you match each shared code to its shared word. Once every word in a sentence except one has been matched to a code, whatever code is left over must stand for that one remaining word.

1. Compare the first statement (‘3a, 2b, 7c’ = ‘Truth is Eternal’) with the second (‘7c, 9a, 8b, 3a’ = ‘Enmity is not Eternal’): the codes common to both are ‘3a’ and ‘7c’, and the words common to both are ‘is’ and ‘Eternal’. So ‘3a’ and ‘7c’ together stand for ‘is’ and ‘Eternal’.

2. Compare the second statement with the third (‘9a, 4d, 2b, 6b’ = ‘Truth does not perish’): the only code common to both is ‘9a’, and the only word common to both is ‘not’. So ‘9a’ means ‘not’.

3. Compare the first statement with the third: the only code common to both is ‘2b’, and the only word common to both is ‘Truth’. So ‘2b’ means ‘Truth’.

4. In the second statement, three of its four codes are now identified — ‘3a’ and ‘7c’ stand for ‘is’ and ‘Eternal’, and ‘9a’ stands for ‘not’. The one code left, ‘8b’, must stand for the one word left over, ‘enmity’.

Checking the second statement in full confirms this: ‘3a’/‘7c’ → ‘is’/‘Eternal’, ‘9a’ → ‘not’, ‘8b’ → ‘enmity’ — all four codes map to all four words with none left unmatched.

So ‘8b’ is the code for ‘enmity’.