Here is the problem

Given: Given f(x) = ( sqrt ( x ) - 3) / (sqrt ( x ) + 3 ).

Find the derivative. I seem to be very weak at my algebra, im not sure what to do after this:

(sqrt (x) +3 (1/2 x ^-1/2 ) - sqrt (x) - 3 (1/2 x ^-1/2 ) / (sqrt (x) +3)^2 This comes from the quotient rule. Can anyone give me some tips to simplify the equation?