A is formed by reversing the digits of B. B is 45 less than A. The sum of the digits of B is 9. What is A?

72

Solving these types of questions with the help of options makes it easy.

Option1 i.e. A = 36 then B = 63, according to question 63 - 36 should be equal to 45 thus, this is not the answer

Option2 i.e. A = 81 then B = 18, according to question 81 - 18 should be equal to 45 thus, this is not the answer

Option3 i.e. A = 54 then B = 45, according to question 54 - 45 should be equal to 45 thus, this is not the answer

Option4 i.e. A = 72 then B = 27, according to question 72 - 27 should be equal to 45 thus, this is the answer