PLEASE HELP!!
posted by Shereen on .
A crate of potatoes of mass 23.0 kg is on a ramp with angle of incline 30° to the horizontal. The coefficients of friction are μs = 0.65 and μk = 0.44. Find the frictional force (magnitude and direction) on the crate if the crate is at rest.

http://www.jiskha.com/display.cgi?id=1316980083
mu is a way of typing the Greek letter "mu", the coefficent of static friction here.