If the length of a rectangle is 10 cm and the width is half the length, what is the perimeter of the rectangle in cm?
一个长方形的长是10厘米，宽是长的一半，这个长方形的周长是多少厘米．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">10 + 5</gadget>
<output>15</output>

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

<result>30</result>