Hi everyone, finished all my utexas physics homework, save this last question... I don't quite why I'm not getting the right answer. Any help offered will be appreciated, it could lead me to the right answer :)

P.S.---- I've already imputed the following four answers which were incorrect. (3844N,8487N,11194N,12925N)

The next curve that the car approaches also
has a radius of curvature 67.4 m. It is banked
at an angle of 30◦. The ideal speed for this
curve is vc (banked so that the car experiences
no frictional force). The speed of the car vs as
it rounds this curve is vs = 0.673 vc.
If the mass of the car is 1500 kg, what is
the magnitude of the frictional force needed
to keep it from sliding sideways?
Answer in units of N.