The width of a rectangle is 3 cm and the length is 5 times the width. What is the perimeter of this rectangle?
一个长方形的宽是3厘米，长是宽的5倍．这个长方形的周长是多少？
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">3 + 15</gadget>
<output>18</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<result>36</result>