The base area of a cuboid is 20 square decimeters. If the base area is increased by 5 square decimeters, how much should the height be reduced to keep the volume of the cuboid constant.
一个长方体底面积是20平方分米，如果底面积增加5平方分米，要使长方体体积不变，高应该减少多少．
<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">25 / 20</gadget>
<output>5/4 = around 1.25</output>

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