Given equation:
6 - 20 ÷ 12 × 7 + 1 = 70
Let's check each option one by one:
Option 1) ÷ and +
After interchanging ÷ and +:
6 - 20 + 12 × 7 ÷ 1 = 70
= 6 - 20 + 84 ÷ 1
= 6 - 20 + 84
= 70
Since 70 = 70, this option is correct.
Option 2) × and -
After interchanging × and -:
6 × 20 ÷ 12 - 7 + 1 = 70
= 120 ÷ 12 - 7 + 1
= 10 - 7 + 1
= 4
Since 4 ≠ 70, this option is incorrect.
Option 3) × and +
After interchanging × and +:
6 - 20 ÷ 12 + 7 × 1 = 70
= 6 - 1.67 + 7
= 11.33 (approx)
Since 11.33 ≠ 70, this option is incorrect.
Option 4) ÷ and ×
After interchanging ÷ and ×:
6 - 20 × 12 ÷ 7 + 1 = 70
= 6 - 34.29 + 1
= -27.29 (approx)
Since -27.29 ≠ 70, this option is incorrect.
Hence, the correct answer is "Option 1".