$3(30$ POINTS$)$

of izontal platform ABCD weighs $60$ lb $.$ and supports a $240-lb$ load at its center $(300$ lb $.$ total$).$ The platform is nally held in position by hinges at A and $B$ and by the brace at $CE.$ Determine the reaction at hinge A and the arce exerted by the brace $CE.$ The hinge at A does not exert any axial thrust.