The simplification required is to remove the root from the denominator of the fraction (so that roots are confined to the numerator).
This may be achieved by multiplying by 1 (so that the value of the overall expression is unchanged), but choosing an appropriately constructed expression that evaluates to 1 (noting that anything divided by itself (excluding zero) equals 1).
The specially chosen instance of 1 requires a number in its denominator that will remove the root. This can be achieved by multiplying by something divided by sqrt(3), as sqrt(3) xx sqrt(3) = 3. To ensure the complete number is 1, the numerator must also have sqrt(3).
So, the required simplification is
(11y)/sqrt(3) xx sqrt(3)/sqrt(3)
(11ysqrt(3))/3