选择题
2024 AMC 8 Problem 3: Overlapping Squares
Four squares of side length 4, 7, 9, and 10 are arranged in increasing size order so that their left edges and bottom edges align. The squares alternate in color white-gray-white-gray, respectively, as shown in the figure. What is the area of the visible gray region in square units?
2024 AMC 8 第3题：重叠的正方形
将边长为 4、7、9 和 10 的四个正方形按尺寸递增的顺序排列，使其左边缘和底边缘对齐。方块的颜色分别为白-灰-白-灰交替，如图所示。可见灰色区域的面积是多少平方单位
A.
42
B.
45
C.
49
D.
50
E.
52