A rectangular frame nailed by wooden strips is 28 cm long and 15 cm wide. After stretching it into a parallelogram, the area is reduced by 56 square centimeters. What is the height in cm on the longer side of the parallelogram?
一个木条钉成的长方形框架，长是28厘米，宽是15厘米，将它拉伸成一个平行四边形后面积减少了56平方厘米．平行四边形较长边上的高是多少厘米？
<gadget id="calculator">28 * 15</gadget>
<output>420</output>

<gadget id="calculator">420 - 56</gadget>
<output>364</output>

<gadget id="calculator">364 / 28</gadget>
<output>13</output>

<result>13</result>