A triangle and a parallelogram have the same area and the same height. It is known that the base of the triangle is 30 cm, so how much is the parallelogram.
一个三角形与一个平行四边形面积相等，高也相等，已知三角形的底是30厘米，那么平行四边形的多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 30</gadget>
<output>15</output>

<result>15</result>