[问答题]
Consider the graphs 3xn ln c3o4w2dof o5m,zzyh tj kt.y-3 l*xd2k3g$y=-\frac{1}{2}|x|$ and y=2|x|-a , where $a \in \mathbb{Z}^{+}$ .
1. Sketch the graphs on the same set of axes.
2. Given that the graphs enclose a region of area 40 square units, find the value of a .
