The length of a rectangular swimming pool is 50 meters and the width is 10 meters. After expansion, the length remains the same. After expansion, the length remains the same and the width increases to 12 meters. After the expansion, the floor area of the swimming pool has increased by how many percent?
一个长方形游泳池的长是50米，宽是10米，扩建后长不变，扩建后长不变，宽增加到12米．扩建后游泳池的占地面积比原来增加了百分之几？
<gadget id="calculator">50 * 12</gadget>
<output>600</output>

<gadget id="calculator">50 * 10</gadget>
<output>500</output>

<gadget id="calculator">600 - 500</gadget>
<output>100</output>

<gadget id="calculator">100 / 500</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>