Symbol swap — If ‘‘−’’ means ‘‘÷’’, ‘‘+’’ means ‘‘−’’, ‘‘÷’’ means ‘‘×’’, and ‘‘×’’ means ‘‘+’’, which equation becomes correct?

Difficulty: Easy

Correct Answer: 70 - 2 + 4 ÷ 5 x 6 = 21

Explanation:


Introduction / Context:
Each printed operator must be replaced by the designated real operator, after which we check which equality holds.


Given Data / Assumptions:

  • Mapping: “−”→“÷”, “+”→“−”, “÷”→“×”, “×”→“+”.
  • Standard arithmetic precedence applies.


Concept / Approach:
Translate the left-hand side (LHS) using the mapping and evaluate; compare with the right-hand side (RHS) constant.


Step-by-Step Solution:
LHS after mapping: 70 ÷ 2 − 4 × 5 + 6.Compute: 70 ÷ 2 = 35; 4 × 5 = 20; so LHS = 35 − 20 + 6 = 21.Hence the equality “= 21” is correct (Option B).


Verification / Alternative check:
Evaluating other RHS values (44, 96, 341) does not match the computed LHS 21.


Why Other Options Are Wrong:
They assert incorrect RHS values for the correctly decoded LHS.


Common Pitfalls:
Replacing symbols but forgetting to keep normal precedence (× and ÷ before + and −).


Final Answer:
Option B is correct.

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