The length of a rectangular playground is reduced by (1/5). To keep the area of the playground unchanged, how much should the width be increased?
一个长方形操场，长减少了它的(1/5)，要使操场的面积不变，宽应增加它的多少
<gadget id="calculator">10 * 5</gadget>
<output>50</output>

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

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">10 * (4/5)</gadget>
<output>8</output>

<gadget id="calculator">50 / 8</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">(25/4) - 5</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) / 5</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>