If ‘SAVE’ is coded as ‘★3#5’, and ‘VASE’ as ‘#3★5’, then what is the code for ‘EVAS’?

Correct — D. Rule: each letter keeps its own symbol, wherever it stands.

SAVE → ★3#5 gives S = ★, A = 3, V = #, E = 5.
VASE → #3★5 uses the same four pairs, so the code is letter for letter.

EVAS: E = 5, V = #, A = 3, S = ★
Code: 5#3★ → option (d)

Why the others are wrong

• (a)
  5★3# — 5★3# puts ★ second, but the second letter of EVAS is V, whose symbol is #. This is the code for ESAV.
• (b)
  ★5#7 — 7 appears in neither given code, so it stands for no letter. The option also opens with ★, the symbol for S, where EVAS opens with E = 5.
• (c)
  ★5#3 — ★5#3 opens with ★, the symbol for S, but EVAS begins with E = 5. It is the code for SEVA: the right four symbols in the wrong order.

In a letter-substitution code, every letter is replaced by a fixed symbol and the letter order is kept.

The second example is the check. SAVE and VASE use the same four letters, and in VASE's code the symbols have moved with their letters: ★ goes from first place to third along with S.

So build EVAS letter by letter from the table, in EVAS's own order.

Key facts

• S = ★, A = 3, V = # and E = 5.
• EVAS is coded 5#3★.
• A letter-substitution code keeps the word's length and letter order.

Common traps

• Swapping the symbols for S and V, which gives 5★3#.
• Picking an option with the right four symbols without checking their order, such as ★5#3.

No directly related past PYQ was found.