If the signs ‘×’ and ‘–’ are interchanged, which of the following equations becomes correct?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 30 × 5 – 4 + 2 = 12
In each option write ‘–’ for every ‘×’ and ‘×’ for every ‘–’, then work out the left side by BODMAS.
Option (3) becomes 30 – 5 × 4 + 2
\(5\times4=20\)
\(30-20+2=12\), which equals the right side
Why the other options are incorrect
Option (1) 9 × 4 – 3 + 6 = 31 — Incorrect. It becomes 9 – 4 × 3 + 6 \(=\) 3, not 31.
Option (2) 15 – 2 × 6 + 4 = 20 — Incorrect. It becomes 15 × 2 – 6 + 4 \(=\) 28, not 20.
Option (4) 8 – 7 × 10 + 5 = 52 — Incorrect. It becomes 8 × 7 – 10 + 5 \(=\) 51, not 52.