Correct Answer: – and ÷

Solution : Given:
21 – 7 × 4 ÷ 10 + 2 = 4

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 –
= 21 × 7 – 4 ÷ 10 + 2
= 147 – 0.4 + 2
= 148.6 ≠ 4
Second option: × and ÷
Solving the L.H.S. of the equation –
= 21 – 7 ÷ 4 × 10 + 2
= 21 – 17.5 + 2
= 5.5 ≠ 4
Third option: – and ÷
Solving the L.H.S. of the equation –
= 21 ÷ 7 × 4 – 10 + 2
= 12 – 10 + 2
= 4 = R.H.S.
Fourth option: + and –
Solving the L.H.S. of the equation –
= 21 + 7 × 4 ÷ 10 – 2
= 21 + 2.8 – 2
= 21.8 ≠ 4

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