If the length of a rectangle is increased by 3 cm and the width by 5 cm, how much will its perimeter increase?
一个长方形的长增加了3厘米，宽增加了5厘米，其周长将增加多少．
<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>