If the base of the triangle is increased by 25%, how much must the height be reduced to keep the area constant?
三角形底增加25%，要使面积不变，高要减少多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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