If the length of a rectangle is increased by 3 cm and the width by 4 cm, by how many cm does its perimeter increase?
把一个长方形的长增加3厘米，宽增加4厘米，它的周长增加了多少厘米
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<result>14</result>