The playground of an elementary school is 70 meters long and 50 meters wide. Now it is planned to expand, the length will be increased by 30 meters, and the width will be increased by 20 meters. Please think about it and do the math, how many square meters has the area of the playground increased?
某小学的操场，长是70米，宽是50米．现在打算扩建，长增加30米，宽增加20米．请你想一想，算一算，这个操场的面积增加了多少平方米？
<gadget id="calculator">70 + 30</gadget>
<output>100</output>

<gadget id="calculator">50 + 20</gadget>
<output>70</output>

<gadget id="calculator">100 * 70</gadget>
<output>7_000</output>

<gadget id="calculator">70 * 50</gadget>
<output>3_500</output>

<gadget id="calculator">7_000 - 3_500</gadget>
<output>3_500</output>

<result>3_500</result>