Cut out the largest triangle from a rectangular paper with an area of 60 square decimeters and a width of 4 decimeters. What is the area of this triangle in square decimeters?
从面积是60平方分米，宽是4分米的长方形纸上剪下一个最大的三角形，这个三角形的面积是多少平方分米．
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<result>30</result>