Two parallelograms of equal area, one with a base length of 4.2 meters and a height of 1.5 meters; the other with a base length of 2.1 meters and a height of how many meters.
面积相等的两个平行四边形，一个底长4.2米，高1.5米；另一个底长2.1米，高多少米．
<gadget id="calculator">1.5 / 2.1</gadget>
<output>0.714286</output>

<gadget id="calculator">4.2 * 0.714286</gadget>
<output>3.000001</output>

<result>3.000001</result>