Physics Homework Help?

Question

A horizontal force of 150 N is used to push a 36.0 kg packing crate a distance of 6.25 m on a rough horizontal surface. If the crate moves at constant speed, find each of the following.
(a) the work done by the 150 N force
I got 937.5 J
(b) the coefficient of kinetic friction between the crate and the surface
????HELP!!

Answer 1

a) W=Fd
W=150 x 6.25=938 confirmed (you need only 3 SF)
b) Ahhh!!!!

F=f=uN
f=umg
u= F/mg= 150/(36.0 x 9.81)=0.425