Question 1194496
<pre>
A number of two digits, written "ab" has value  10a + b

4(a+b) = 10a + b              (eq 1)

Reversing the digits means writing it as "ba" which has value 10b + a:

10b + a = (10a + b) + 27      (eq 2)

Simplify both equations:
(eq 1) simplifies to  2a - b = 0  ---> b = 2a
(eq 2) simplifies to   b - a = 3  
Using substitution (b = 2a) into the simplified (eq 2)  gives
      2a - a = 3     or    a = 3   --->  b = 6
The number is {{{ highlight(36) }}}

Check:
4(3+6) = 4*9 = 36  (ok on first condition)
63 = 27 + 36    (ok on 2nd condition)