For a rectangle, subtract (2/5) from its length and add (2/5) meters to its width, and its area remains the same. What is the width of this rectangle in meters?
一个长方形，把它的长减去(2/5)，宽增加(2/5)米，其面积不变，原来这个长方形的宽是多少米．
<gadget id="calculator">6 / 25</gadget>
<output>6/25 = around 0.24</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(6/25) / (2/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>