Correct Answer: ÷ and +

Solution : Given:
24 ÷ 15 × 16 + 4 – 18 = 66

Replace the given symbols in the options one by one with the original symbols in the given equation.
First option: ÷ and ×
Solving the L.H.S. of the equation –
= 24 × 15 ÷ 16 + 4 – 18
= 22.5 – 14
= 8.5 ≠ 66
Second option: – and +
Solving the L.H.S. of the equation –
= 24 ÷ 15 × 16 – 4 + 18
= 1.6 × 16 – 4 + 18
= 25.6 + 14
= 39.6 ≠ 66
Third option: – and ×
Solving the L.H.S. of the equation –
= 24 ÷ 15 – 16 + 4 × 18
= 1.6 – 16 + 72
= 57.6 ≠ 66
Fourth option: ÷ and +
Solving the L.H.S. of the equation –
= 24 + 15 × 16 ÷ 4 – 18
= 24 + 15 × 4 – 18
= 24 + 60 – 18
= 66 = R.H.S.

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