If "CAT" is coded as "3-1-20", how will "TAC" be coded?

Correct — A.
Rule: each letter is coded by its alphabet position: C = 3, A = 1, T = 20.

TAC uses the same letters in a new order.
T = 20, A = 1, C = 3
So TAC is coded 20-1-3 → option (a).

Why the others are wrong

• (b)
  3-20-1 — 3-20-1 spells C, T, A: the right numbers in the wrong order. TAC starts with T, so its code starts with 20.
• (c)
  1-3-20 — 1-3-20 spells A, C, T. TAC begins with T (20), not A (1).
• (d)
  20-3-1 — 20-3-1 spells T, C, A. It starts correctly but swaps the last two: TAC ends A then C, so 1 then 3.

The simplest letter code is alphabet position: A = 1, B = 2 … Z = 26. 'CAT = 3-1-20' confirms it at once, since C, A and T sit at 3, 1 and 20.

When the new word uses the same letters in another order, no arithmetic is needed: reorder the same numbers to follow the new spelling.

TAC is CAT reversed, so its code is 3-1-20 reversed.

Key facts

• Positions worth memorising: E 5, J 10, O 15, T 20, Y 25.
• Reversing a word reverses its position code: CAT is 3-1-20, TAC is 20-1-3.

Common traps

• Choosing 20-3-1, which starts right with T but keeps C ahead of A.

No directly related past PYQ was found.