Correct Answer: × and ÷

Solution : Given:

6 ÷ 17 × 51 + 6 – 12 = –4

Let's check the options —

First option: × and ÷;

After interchanging the signs, the equation becomes 6 × 17 ÷ 51 + 6 – 12 = –4. So, this option is correct.

Second option: + and ÷;

After interchanging the signs, the equation becomes 6 + 17 × 51 ÷ 6 – 12 = 138.5. This is not equal to –4. So, this option is not correct.

Third option: + and –;

After interchanging the signs, the equation becomes 6 ÷ 17 × 51 – 6 + 12 = 24. This is not equal to –4. So, this option is not correct.

Fourth option: – and ÷;

After interchanging the signs, the equation becomes 6 – 17 × 51 + 6 ÷ 12 = –860.5. This is not equal to –4. So, this option is not correct.

Hence, the first option is correct.