A 100-kg box on the right and a 45-kg box on the left are tied together by a horizontal cable. The 100-kg box is acted upon by an external force of 560 N to the right. The frictional force exerted by the floor on the 100-kg box is 40 N and the frictional force exerted by the floor on the 45-kg box is 15 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 100-kg block?