If the lengths of the three sides of a triangle are 10 cm, 20 cm, and 20 cm, what is its perimeter in decimeters?
一个三角形三边长分别是10厘米、20厘米、20厘米，它的周长是多少分米．
<gadget id="calculator">10 + 20 + 20</gadget>
<output>50</output>

<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<result>5</result>