Correct Answer: 40, 50

Solution : Given:
16 × 5 ÷ 20 + 6 + 50 = 40

Replace the given numbers in the options one by one with the original numbers in the given equation.
First option: 40, 50
⇒ 16 × 5 ÷ 20 + 6 + 40 = 50
= 4 + 6 + 40
= 50
Second option: 6, 40
⇒16 × 5 ÷ 20 + 40 + 50 = 6
= 4 + 40 + 50
= 94 ≠ 6
Third option: 20, 40
⇒ 16 × 5 ÷ 40 + 6 + 50 = 20
= 2 + 6 + 50
= 58 ≠ 20
Fourth option: 5, 40
⇒ 16 × 40 ÷ 20 + 6 + 50 = 5
= 32 + 6 + 50
= 88 ≠ 5

Here, only the first option satisfies the R.H.S. of the given equation. Hence, the first option is correct.