If a rectangle with a length of 8 cm and a width of 5 cm is increased by 2 cm in both length and width, how many square centimeters does the area of the rectangle increase?
一个长8厘米、宽5厘米的长方形，长和宽都增加2厘米，这个长方形的面积增加了多少平方厘米．
<gadget id="calculator">8 + 2</gadget>
<output>10</output>

<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">10 * 7</gadget>
<output>70</output>

<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">70 - 40</gadget>
<output>30</output>

<result>30</result>