A rectangular nursery is 35 meters long and has an area of 420 square meters. If the length increases to 70 meters and the width remains the same, what is the area of the enlarged nursery? (please use two methods to answer)
一个长方形苗圃长35米，面积为420平方米．如果长增加增加到70米，宽不变，扩大后的苗圃面积是多少呢？(请用两种方法解答)
<gadget id="calculator">70 - 35</gadget>
<output>35</output>

<gadget id="calculator">420 / 35</gadget>
<output>12</output>

<gadget id="calculator">35 * 12</gadget>
<output>420</output>

<gadget id="calculator">420 + 420</gadget>
<output>840</output>

<result>840</result>