The area of a rectangle is 78 square meters, and its length is 12 meters. If the width remains the same, if its length is increased by 2 meters, how many square meters will its area increase?
一个长方形的面积是78平方米，它的长是12米，如果宽不变，将它的长增加2米，它的面积增加了多少平方米．
<gadget id="calculator">78 / 12</gadget>
<output>13/2 = around 6.5</output>

<gadget id="calculator">(13/2) * 2</gadget>
<output>13</output>

<result>13</result>