Correct Answer: 7 + 21 × 42 ÷ 14 – 9 = 19

Solution : Given:
÷ and +

Replace the given symbols in the options one by one with the original symbols in the given equation.
First option: 18 ÷ 24 – 6 × 6 + 3 = 32
= 18 + 24 – 6 × 6 ÷ 3 = 32
= 42 – 12
= 30 ≠ 32
Second option: 12 – 8 + 12 × 9 ÷ 3 = 10
= 12 – 8 ÷ 12 × 9 + 3 = 10
= 12 – 6 + 3
= 9 ≠ 10
Third option: 12 ÷ 8 × 3 + 6 – 10 = 8
= 12 + 8 × 3 ÷ 6 – 10 = 8
= 12 + 4 – 10
= 6 ≠ 8
Fourth option: 7 + 21 × 42 ÷ 14 – 9 = 19
= 7 ÷ 21 × 42 + 14 – 9 = 19
= 14 + 14 – 9
= 19 = R.H.S.

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