If the length of a rectangle is 9 cm and the width is 60 mm, what is its perimeter in cm?
一个长方形的长是9厘米，宽是60毫米，它的周长是多少厘米．
<gadget id="calculator">60 / 10</gadget>
<output>6</output>

<gadget id="calculator">9 + 6</gadget>
<output>15</output>

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

<result>30</result>