If the length of a rectangle is increased by (1/4), how much should the width be reduced to keep the area constant?
一个长方形，长增加(1/4)，要使面积不变，宽应减少多少
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">2 * 1 * (5/4)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">1 / (5/2)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">2 * (2/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

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

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