A light board, 10 m long, is supported by two sawhorses, one at one edge of the board and a second at the midpoint. A 40-N weight is placed between the two sawhorses, 3.0 m from the edge and 2.0 m from the center. A second weight with a mass of 15 N, is placed at the end of the board. What is the force exerted by the sawhorse at the end of the board?