A skier is going down a hill with a coefficient of friction of 0.21 and an angle of 7.5 degrees. if the skier has an initial velocity of 30 m/s, how fast will she be going after 10 s

vf=vi+at

but a= netforce/mass

a= (mg*cosTheta-mg*mu*sinTheta)/m
a= g(cosTheta-mu*sinTheta

solve for vf.