If + = ×, − = ^, × = −, evaluate: 5 − 2 × 3 + 1

Correct — A.
Rule: substitute all three signs, then powers before × and −.

Printed: 5 − 2 × 3 + 1
Substituted: 5 ^ 2 − 3 × 1

Power: 5 ^ 2 = 5² = 25
Multiplication: 3 × 1 = 3
Subtraction: 25 − 3 = 22 → option (a).

Why the others are wrong

• (b)
  23 — 23 is 25 − 3 + 1, which leaves the printed + as addition. The code turns + into ×, so the tail is 3 × 1 = 3 and the value is 22.
• (c)
  24 — 24 is 25 − 1. It would need 3 × 1 to be 1, but 3 × 1 = 3, so 25 − 3 = 22.
• (d)
  25 — 25 is 5² alone, before anything is taken away. The substituted expression still has − 3 × 1 to apply, which brings it to 22.

This code has three substitutions: + becomes ×, − becomes ^ (raise to a power), and × becomes −. Swap all three before any arithmetic.

Then keep the order of operations: powers first, then × and ÷, then + and −. 5 ^ 2 is worked first, then 3 × 1, and only then the subtraction.

Key facts

• The code: + is ×, − is ^ (power), × is −.
• 5 − 2 × 3 + 1 becomes 5 ^ 2 − 3 × 1.
• Powers come before multiplication, and multiplication before subtraction.

Common traps

• Replacing − and × but leaving + as addition, which gives 23
• Stopping at 5² = 25 and choosing option (d)

No directly related past PYQ was found.