The following equation is incorrect. Which of the following two signs should be interchanged to correct the equation? 18 + 6 × 4…

Question

The following equation is incorrect.

Which of the following two signs should be interchanged to correct the equation? 18 + 6 × 4 – 12 ÷ 3 = 17

1. A. + and ×
2. B. × and ÷
3. C. + and –
4. D. – and ÷ (Correct answer)

Correct Answer

Option D — – and ÷

Detailed Solution & Explanation

The correct answer is – and ÷.

Key Points

• Test each proposed swap on 18 + 6 × 4 – 12 ÷ 3 = 17 and evaluate with BODMAS:
• Swap + and ×: 18 × 6 + 4 – 12 ÷ 3 = 108 + 4 − 4 = 108 ✗
• Swap × and ÷: 18 + 6 ÷ 4 – 12 × 3 = 18 + 1.5 − 36 = −16.5 ✗
• Swap + and –: 18 – 6 × 4 + 12 ÷ 3 = 18 − 24 + 4 = −2 ✗
• Swap – and ÷: 18 + 6 × 4 ÷ 12 – 3 = 18 + 2 − 3 = 17 ✓
• Only the last interchange balances the equation.