Which two numbers need to be interchanged to make the given equation correct?
$$72 \times 9 + 27 \div 3 - 6 = 213$$

Option (a) 9, 6

$$72 \times 6 + 27 \div 3 - 9 = 213$$

$$432 + 9 - 9 = 213$$

$$432\ne213$$

The given equation is not satisfied. So this is not the correct answer.

Option (b) 9 ,3

$$72 \times 3 + 27 \div 9 - 6 = 213$$

$$216 + 3 - 6 = 213$$

213 = 213

The given equation is satisfied. So this is the correct answer.

Option (c) 72, 27

$$27 \times 9 + 72 \div 3 - 6 = 213$$

$$243 + 24 - 6 = 213$$

$$261\ne213$$

The given equation is not satisfied. So this is not the correct answer.

Option (d) 72, 6

$$6 \times 9 + 27 \div 3 - 72 = 213$$

$$54 + 9 - 72 = 213$$

The given equation is not satisfied. Because the obtained value is negative. So this is not the correct answer.