A4.00 kg box sits atop a 10.0 kg box on a horizontal table. the coefficient of kinetic friction between the two boxes and between the lower box and the table is 0.600, while the coefficient of static friction between these same surfaces is 0.800. a horizontal pull to the right (150 n) is exerted on the lower box, and the boxes move together. what is the magnitude and direction of the friction force on the upper box?