Question 754662
You must use a method called rationalisation.
You multiply your equation by sqroot8/sqroot8 
which is really equal to 1/1 or 1

       2/ 6 sqroot8  x  sqroot8/sqroot8  

            = 2 sqroot 8/ 6 x 8   (sqroot8 x sqroot8 = 8)

                 sqroot 8 = 2 sqroot 2

            (So your 2sqroot 8 becomes 4 sqroot 2)

             Equation is:-  4 sqroot 2/ 48

             Cancel 4 and 48  and you are left with:-

                           sqroot 2/12

 Hope this helps
:-)