Find f'(x) if f(x) = ln((8x+4)/(9x-7))^(1/2)

Thank you very much for your time.

f(x) = 1/2 ln (8x+4)/(9x-7)

= 1/2 (ln(8x+4) - ln(9x-7))
= 1/2 ln(8x+4) - 1/2 ln(9x-7)

f' = 4/(8x+4) - 9/[2(9x-7)]
= (18x-23)/[2(2x+1)(9x-7)]