The sum of the digits of a two-digits numbers is 12 and when the digits of the to digit number are interchanged, the new number is 36 more than the original. What is the Original number?

Answer: Option B

Let the Original number is (X + 10Y)
According to question,
Sum of the digit of the number = 12
X + Y = 12 ----------- (1) When digit interchanged, number become 36 more than original number, so,
10X + Y = 10Y + X + 36
X - Y = 4 ------------------- (2)
On solving equation (1) and (2), we get
X = 8
Y = 4
So, Original number,
= X + 10Y = 8 + 10 × 4 = 48