multiply the numerator and denominator of the given fraction by (sqrt(10x+5)-5), and you will have

(sqrt(3x+3)-3)*(sqrt(10x+5)-5)

lim -----------------------------------

x->2 (sqrt(10x+5)-5)*(sqrt(10x+5)-5)

NOTE that the denominator above is in the form of (a-b)(a-b), which is equal to a^2-2ab+b^2

(sqrt(3x+3)-3)*(sqrt(10x+5)-5)

= lim --------------------------------------

x->2 (10x+5) - 2*5*(sqrt(10x+5)-5) + 25

calculate the limit as x-> 2, you should get 0.