Question 1058733
The sum of the digits of a 2-digit number is 15.  The digits 
are reversed when 27 is subtracted from given number.  
What is the the two-digit number?
<pre>
The tens digit = t
The units digit = u
The number = 10t+u
The number reversed = 10u+t

The sum of the digits of a 2-digit number is 15.  

t+u = 15


The digits are reversed when 27 is subtracted from given number.

10t+u - 27 = 10u+t

Which simplifies to

9t-9u = 27

or dividing through by 9

t-u = 3

Adding the two equations:

t+u = 15
t-u =  3
--------
 2t = 18
  t =  9

Substituting in

t+u = 15
9+u = 15
  u =  6

The number is "tens digit, units digit" or 96.

Checking the sum of the digits is 9+6=15.

Subtracting 27 from 96 give 96-27 = 69.

That's 96 with the digits reversed.

So the answer is correct.

Edwin</pre>