Given that the length of the rectangle increases (1/6), how much must the width be reduced in order to keep the area constant.
已知长方形的长增加(1/6)，要使面积不变，宽减少多少．
<gadget id="calculator">7 / 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>