Four pieces of lumber (planks of wood) are placed in parallel positions, as shown below, perpendicular to the line W. Piece A is 5 m long and touches W Piece B is 3 m long and its left end is 3 m from the line W Piece C is 5 m long and its left end is 2 m from the line W Piece D is 4 m long and its left end is 1.5 m from the line W a A B C D W L A single cut, parallel to W, is made along the dotted line L. The total length of lumber on each side of L is the same. What is the length, in m, of the part of A to the left of the cut (the length, a, in the diagram)? Remember to show all your work for full marks.