如图，有一块不规则的四边形地皮ABCD，各个顶点的坐标分别为A（-2，6），B（-5，4），C（-7，0），O（0，0）（图上一个单位长度表示10米），现在想对这块地皮进行规划，需要确定它的面积．（1）求这个四边形的面积；（2）如果把四边形ABCD的各个顶点的纵坐标保持不变，横坐标加2，所得到的四边形面积是多少？---**Chart/Diagram Description:**
* **Type:** Coordinate plane with a geometric figure.
* **Coordinate Axes:** A horizontal x-axis and a vertical y-axis intersect at the origin O. The positive x-axis extends to the right, and the positive y-axis extends upwards. Arrows indicate the positive direction of both axes.
* **Grid:** The background is a grid of dashed lines forming squares. Each square represents one unit in both the x and y directions.
* **Points:**
* Origin O is located at the intersection of the x and y axes, with coordinates (0, 0).
* Point A is located at (-1, 4).
* Point B is located at (-3, 2).
* Point C is located at (-5, 0).
* **Lines:** Straight line segments connect the points in the order C to B, B to A, A to O, and O to C, forming a closed figure.
* **Shape:** The figure formed by connecting points O, A, B, and C in order is a quadrilateral OABC. The vertices are O(0,0), A(-1,4), B(-3,2), and C(-5,0).
* **Labels:** The axes are labeled 'x' and 'y'. The origin is labeled 'O'. The vertices are labeled 'A', 'B', and 'C'.