If the length of a rectangle is extended (1/6), how much should the width be shortened to keep the area constant.
一个长方形如果把长延长(1/6)，那么宽应缩短多少才能使面积不变．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 + (1/6)</gadget>
<output>7/6 = around 1.166667</output>

<gadget id="calculator">1 / (7/6)</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">1 - (6/7)</gadget>
<output>1/7 = around 0.142857</output>

<result>1/7 = around 0.142857</result>