Answer:
39
Explanation:
Let x be tens place digit and y be units place digit.
Therefore, required number = 10x + y
On reversing the digits number so obtained = 10y + x
According to the given information:
10y + x = 10x + y + 54
10y + x - 10x - y = 54
9y - 9x = 54
9(y - x) = 54
y - x = 54/9
y - x = 6
y = x + 6...... (1)
Since, sum of the digits is 12.
Therefore, x + y = 12....(2)
From equations (1) & (2)
x + x + 6 = 12
2x = 12 - 6
2x = 6
x = 6/2
x = 3
y = x + 6 = 3 + 6 = 9...[from eqn (2)]
10x + y = 10*3 + 9 = 30 + 9 = 39
Thus, the required number is 39.