If a sector with a central angle of 72° is cut from a circle with an area of 40 square decimeters, what is the area of the remaining part?
在一个面积为40平方分米的圆中剪去一个圆心角为72°的扇形，剩余部分的面积是多少平方分米．
<gadget id="calculator">72 / 360</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 * (4/5)</gadget>
<output>32</output>

<result>32</result>