Answer:
x=3mod4
Means that when x is divided by 4 it gives an unknown integer and a remainder of 3.
x/4 = Z + 3/4
Z= (x-3)/4
Where Z is the integer
x=5 mod6
x/6 = Y + 5/6
Y = (x-5)/6
Where Y is the integer
Z-Y must be an integer on equal to zero
(x-3)/4 - (x-5)/6
3(x-3)/12 - 2(x-5)/12
(3x-9-2x+10)/12
(x+1)/12
If it is equal to 0
x=-1. But x should be positive
If it is equal to 1
x=11
Hence the smallest possible number is 11