A 105-kg box on the right and a 40-kg box on the left are tied together by a horizontal cable. The 105-kg box is acted upon by an external force of 550 N to the right. The frictional force exerted by the floor on the 105-kg box is 35 N and the frictional force exerted by the floor on the 40-kg box is 20 N. In this problem, orient your axes such that the right direction is positive and the left direction is negative. What is the net force on the 105-kg block?