A triangle has an area of 30 square centimeters, a height of 5 centimeters, and a base of centimeters.
一个三角形，它的面积是30平方厘米，高是5厘米，底是多少厘米．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">30 * (2/5)</gadget>
<output>12</output>

<result>12</result>