If the length of the rectangle is increased by 1/4, how much must the width be reduced to keep the area constant?
长方形的长增加(1/4)，要使面积不变，宽必须减少多少
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 * (1/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) - 2</gadget>
<output>-3/2 = around -1.5</output>

<gadget id="calculator">2 + (-3/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 + (1/2)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(1/2) / (5/2)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>