A parallelogram and a triangle have the same area and height. The base of the parallelogram is 30 cm. What is the base of the triangle in cm?
一个平行四边形和一个三角形面积相等高相等，平行四边形的底是30厘米，三角形的底是多少厘米．
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<result>60</result>