When the triangle is removed, it creates the shaded region

A right triangle is removed from the rectangle in the figure below.  When the triangle is removed, it creates the shaded region.  Find the  area of the shaded region.

Part I – What is the area of the triangle (20%)

Part II – What is the area of the rectangle (20%)

Part III – What is the area of the shaded region? How did you determine that area? (40%)

Part IV – Review and comment on ONE classmate’s post; provide a comment for each part of the posting. (20%)

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