Question 309030
Basic facts:
1. 2 digit figure say xy can also be written as 10x + y where y is the digit in the units place and x is the digit in the tens place
Eg., 56 = 5x10 + 6

As per the question, in the original number let the digit in the tens place be x
Therefore the other digit in units place is x/2
Therefore the original number : 10x + x/2

When the digits are reversed the digit in the tens place becomes x/2
and the digit in the units place becomes x
Hence the new reversed number is 10x/2 + x

As per the question when both the numbers are added the sum is 99.

Therefore the equation is:

(10x + x/2) + (10x/2 + x)=99
or, 10x + x/2 + 5x + x = 99
or, (10x x 2 + x + 5x x 2 + x x 2) / 2 = 99
or, (20x + x + 10x + 2x)= 99 x 2
or, 33x = 198
or, x = 198/33
or x = 6

hence one digit is 6 and the other digit is 3

Therefore the original number is 63

NOTE:
As this is a tricky qs please note that if the digit in tens place is taken as x/2 and that in the units place is taken as x, the answer will be 36.