The original design of a building site is 60 meters long and 30 meters wide. Now it is necessary to expand the area of the real estate. The length remains the same and the width is increased by 15 meters. How much is the expanded area larger than the original design?
某建筑工地原来设计的楼基长60米，宽30米，现在要扩大楼盘面积，长不变而宽增加15米，扩大后的面积比原设计的增加了多少？
<gadget id="calculator">30 + 15</gadget>
<output>45</output>

<gadget id="calculator">60 * 45</gadget>
<output>2_700</output>

<gadget id="calculator">60 * 30</gadget>
<output>1_800</output>

<gadget id="calculator">2_700 - 1_800</gadget>
<output>900</output>

<result>900</result>