a light board that is 10 m long is supported by two sawhorses, one at one end of the board and a second at the midpoint. a 48-n object is placed between the two sawhorses, 3.2 m from the end and 2.2 m from the center. a second object, with a weight of 15 n, is placed on the supported end. what magnitude forces do the sawhorses exert on the board?