Correct Answer: 12 and 24

Solution : Given:
120 ÷ 12 × 6 + 24 – 15 = 27

Replace the given numbers according to the options one by one with the original numbers in the given equation.
First option: 12 and 6
120 ÷ 12 × 6 + 24 – 15 = 27
= 120 ÷ 6 × 12 + 24 – 15
= 240 + 9
= 249 ≠ 27
Second option: 12 and 15
120 ÷ 12 × 6 + 24 – 15 = 27
= 120 ÷ 15 × 6 + 24 – 12
= 48 + 12
= 60 ≠ 27
Third option: 12 and 24
120 ÷ 12 × 6 + 24 – 15 = 27
= 120 ÷ 24 × 6 + 12 – 15
= 30 – 3
= 27
Fourth option: 6 and 24
120 ÷ 12 × 6 + 24 – 15 = 27
= 120 ÷ 12 × 24 + 6 – 15
= 240 – 9
= 231 ≠ 27

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