If the perimeter of a rectangle is 24 cm, if the length and width are increased by 3 cm, the area of the new rectangle will be increased by how many square centimeters compared to the original area.
一个长方形周长24厘米，如果长和宽各增加3厘米，所得新长方形的面积比原来增加多少平方厘米．
<gadget id="calculator">24 / 2</gadget>
<output>12</output>

<gadget id="calculator">3 * 12</gadget>
<output>36</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">36 + 9</gadget>
<output>45</output>

<result>45</result>