Interchange one pair of signs to make the equation true: 16 − 21 ÷ 7 × 6 + 3 = 31

Introduction / Context:
Choose a global swap of one pair of operators so the equality holds.

Given Data / Assumptions:

• Original: 16 − 21 ÷ 7 × 6 + 3.
• Target: 31.

Concept / Approach:
Try each swap and evaluate with precedence.

Step-by-Step Solution:
Swap “+” and “×” (Option B): 16 − 21 ÷ 7 + 6 × 3.Compute: 21 ÷ 7 = 3; so 16 − 3 + (6 × 3 = 18) = 31 ✔.

Verification / Alternative check:
Other options give results like 9, −5.5, etc., not 31.

Why Other Options Are Wrong:
They fail to compensate the large middle product/division segment to hit 31.

Common Pitfalls:
Applying the swap to only one occurrence or changing evaluation order.

Final Answer:
+ and x.