Correct Answer: ÷ and –

Solution : Given:
15 × 18 – 6 ÷ 20 + 4 = 29

Replace the given signs in the options one by one with the original signs in the given equation.
First option: + and ×
= 15 + 18 – 6 ÷ 20 × 4
= 15 + 18 – 0.3 × 4
= 15 + 18 – 1.2
= 31.8 ≠ 29
Second option: ÷ and –
= 15 × 18 ÷ 6 – 20 + 4
= 15 × 3 – 20 + 4
= 45 – 20 + 4
= 29 = R.H.S.
Third option: + and ÷
= 15 × 18 – 6 + 20 ÷ 4
= 15 × 18 – 6 + 5
= 270 – 6 + 5
= 269 ≠ 29
Fourth option: – and +
= 15 × 18 + 6 ÷ 20 – 4
= 15 × 18 + 0.3 – 4
= 270 + 0.3 – 4
= 270.3 – 4
= 266.3 ≠ 29

So, only the second option satisfies the R.H.S. of the given equation. Hence, the second option is correct.