A symmetrical, 2.0 m long, leaning bookshelf (m, 20.0 kg) leans up against a vertical wall, making an angle of 45.0 degrees with respect to the floor. The bookshelf remains secured to the floor, stopping it from slipping. The center of mass acts at the geometric center of the bookshelf. A stack of books (m, = 3.00 kg) is placed 1.50 m up the bookshelf. What is the normal force, in N, exerted by the floor on the bookshelf