Brian is trying to pull Julie on a sled across a flat snowy field. Brian puls on a rope attached to the sled. Brian's pulling force is directed forward and upward at an angle of 30 degrees above horizontal. Julie's mass of 50kg, and the sled's mass is 8kg. If the coefficient of static friction between the sled runners and the snow is 0.10, how much force must Brian exert on the rope to start moving the sled?