Correct Answer: 35 – 51

Solution : Let's check the options –
First option: 24 – 42→On reversing the digits, 24 becomes 42.
Second option: 36 – 63→On reversing the digits, 36 becomes 63.
Third option: 37 – 73→On reversing the digits, 37 becomes 73.
Fourth option: 35 – 51→On reversing the digits, 35 becomes 53 ≠ 51

So, the fourth option is different from the other three options as the second number is not the reverse digit of the first number. Hence, the fourth option is correct.