If the length of a rectangle is increased by 5 cm and the width by 3 cm, what is the increase in its perimeter?
一个长方形的长增加5厘米，宽增加3厘米，它的周长增加多少厘米．
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

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

<result>16</result>