A rectangular vegetable field is 80 meters long and 60 meters wide. If its width is extended to make it a square, then the area of the vegetable field will increase by how many square meters.
一块长方形菜地长80米，宽60米，如果延长它的宽，使它成为一个正方形，那么菜地的面积比原来增加多少平方米．
<gadget id="calculator">80 * 80</gadget>
<output>6_400</output>

<gadget id="calculator">80 * 60</gadget>
<output>4_800</output>

<gadget id="calculator">6_400 - 4_800</gadget>
<output>1_600</output>

<result>1_600</result>