If the width of a rectangle is 5 cm and the length is 4 times the width, what is its perimeter in cm?
长方形的宽是5厘米，长是宽的4倍，它的周长是多少厘米．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>