A triangle and a parallelogram have the same base and height. It is known that the area of the triangle is 15 square centimeters. What is the area of the parallelogram?
一个三角形和一个平行四边形的等底等高，已知这个三角形的面积为15平方厘米，这个平行四边形的面积为多少．
<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<result>30</result>