The area of a sector is (2/5) of the area of the circle on which it is located. What is the central angle of the sector?
一扇形面积是所在圆面积的(2/5)，扇形的圆心角是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">360 * (2/5)</gadget>
<output>144</output>

<result>144</result>