Question 927832
Let 10t+u = The Number
      t+u = The Digits

If the number is divided by the sum of the digits, the quotient is 4.
10t+u
----- = 4
 t+u

Multiply each side by t+u

10t+u=4(t+u)
10t+u=4t+4u
   6t=3u
Divide the whole equation by 3
   2t=u

A number is between 30 and 40.
   30 < 10t+2t < 40
   30 <   12t  < 40
30/12 <    t   < 40/12
  2.5 <    t   < 3.33
t = 3
u = 6

Since the unit digit is twice the tens digit and should be in a range between
30 and 40, the only number applicable with this boundaries is 36.

Check
3+6=9
36/9=4