Correct Answer: 5 and 7; – and ÷

Solution : Given:
25 – 9 + 42 ÷ 6 × 7 = 17

Let's check each option –
First option: 9 and 6, + and ×
On interchanging the mathematical signs and digits, we get –
25 – 6 × 42 ÷ 9 + 7 = 17
On solving the L.H.S. of the equation –
= 25 – 6 × 42 ÷ 9 + 7
= 25 –  28 + 7
= 4 ≠ 17
Second Option: 2 and 5, ÷ and ×
On interchanging the mathematical signs and digits, we get –
52 – 9 + 42 × 6 ÷ 7 = 17
On solving the L.H.S. of the equation –
= 52 –  9 + 42 × 6 ÷ 7
= 52 –  9 + 36
= 79 ≠ 17
Third Option: 5 and 7, – and ÷
On interchanging the mathematical signs and digits, we get –
27 ÷ 9 + 42 – 6 × 5 = 15
On solving the L.H.S. of the equation –
= 27 ÷ 9 + 42 – 6 × 5
= 3 + 42 – 6 × 5
= 3 + 42 – 30
= 15
Fourth option: 4 and 6, + and ÷
On interchanging the mathematical signs and digits, we get –
25 – 9 ÷ 62 + 4 × 7 = 17
On solving the L.H.S. of the equation –
= 25 – 9 ÷ 62 + 4 × 7
= 25 – 0.145 + 4 × 7
= 25 – 0.145 + 28
= 52.855 ≠ 17

So, only the third option satisfies the equation. Hence, the third option is correct.