Question 997835
Call the tens digit x and the ones digit y.
Thus x + y = 7
Originally the value is 10x + y.
Reversed its value is 10y + x.  This is 27 more than the original, so
10y + x = 10x + y + 27
or
-9x + 9y = 27
or
-x + y = 3   now add the first equation and get
x + y = 7
2y = 10 
y = 5
x = 2
The original number was 25.