physics please help
posted by emmie .
A 65 kg bungee jumper leaps from a bridge. She is tied to a bungee cord that is 11m long when unstretched, and falls a total of 30m .
Part a) Calculate the spring constant of the bungee cord assuming Hooke's law applies.
part b)Calculate the maximum acceleration she experiences.
i got the answer for part a which is 105.8 but i need help with part b

b) While falling freely, her acceleration remains g = 9.8 m/s^2 (positive downward). There is another relative maximum acceleration, in the opposite direction, at maximum stretch, X = 19 m. Acceleration then equals
Fnet/m = (kX +Mg)/M
If your k is correct, that would be
(105.8*19 +65*9.8)/65 = 21.1 m/s^2