Correct Answer: 5 and 20, − and ×

Solution : Given:
72 ÷ 6 − 20 + 30 × 5 = 70
Replacing the given numbers and signs in the equation.

First option: 5 and 20, − and ×
72 ÷ 6 × 5 + 30 − 20 = 70
⇒ 12 × 5 + 30 − 20 = 70
= 60 + 30 − 20 = 70
= 90 − 20 = 70
L.H.S = R.H.S
Second option: 20 and 30, × and ÷
72 × 6 − 30 + 20 ÷ 5 = 70
⇒ 72 × 6 − 30 + 4 = 70
= 432 − 30 + 4 = 70
= 432 − 26 = 406 ≠ 70
L.H.S ≠ R.H.S
Third option: 5 and 70, + and −
72 ÷ 6 + 20 − 30 × 70 = 5
⇒ 12 + 20 − 30 × 70 = 5
= 12 + 20 − 2100 = 5
= 12 − 2080 = −2068 ≠ 5
L.H.S ≠ R.H.S
Fourth option: 6 and 20, + and ÷
72 + 20 − 6 ÷ 30 × 5 = 70
⇒ 72 + 20 − 0.2 × 5 = 70
= 72 + 20 − 1 = 70
= 92 − 1 = 91 ≠ 70
L.H.S ≠ R.H.S

So, only the first option satisfies the given equation. Hence, the first option is correct.