Mingpeng took a rectangular photo with an area of 20 square decimeters. Given that the length of this picture is 5 decimeters, what is the width in decimeters?
明鹏拍了一张面积为20平方分米的长方形照片．已知这张照片的长是5分米，则宽是多少分米．
<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<result>4</result>