如图,计算图中阴影所示陆地的面积S(长度单位:m).
【解答】解:a+2a+2a+2a+a=8a,
2.5a+1.5a=4a,
8a×4a﹣2.5a×2a×2
=32a2﹣10a2
=22a2(cm2).
故答案为:22a2.