Which two numbers (not digits) should be interchanged to make the following equation correct?
$$(4 \times 12 + 15) \div 8 - 9 = 0$$

Option (a) 12 and 15

$$(4 \times 15 + 12) \div 8 - 9 = 0$$

$$(60 + 12) \div 8 - 9 = 0$$

$$72 \div 8 - 9 = 0$$

9 - 9 = 0

0 = 0

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

Option (b) 4 and 8

$$(8 \times 12 + 15) \div 4 - 9 = 0$$

$$(96 + 15) \div 4 - 9 = 0$$

$$111 \div 4 - 9 = 0$$

The given equation is not satisfied. So this is not the correct answer. Because it will give values in decimals.

Option (c) 12 and 8

$$(4 \times 8 + 15) \div 12 - 9 = 0$$

$$(32 + 15) \div 12 - 9 = 0$$

$$47 \div 12 - 9 = 0$$

The given equation is not satisfied. So this is not the correct answer. Because it will give values in decimals.

Option (d) 8 and 9

$$(4 \times 12 + 15) \div 9 - 8 = 0$$

$$(48 + 15) \div 9 - 8 = 0$$

$$63 \div 9 - 8 = 0$$

7 - 8 = 0

The given equation is not satisfied. So this is not the correct answer. Because it will give a negative value.