The length of a rectangle is 12 cm and its length is 3 cm longer than its width, what is the perimeter of the rectangle in cm
一个长方形的长是12厘米，它比宽长3厘米，这个长方形的周长是多少厘米
<gadget id="calculator">12 - 3</gadget>
<output>9</output>

<gadget id="calculator">12 + 9</gadget>
<output>21</output>

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<result>42</result>