The school originally had a rectangular playground, 40 meters long and 30 meters wide. When the campus was expanded, the length increased to 50 meters and the width increased to 8 meters. What is the area of the playground after expansion?
学校原来有一个长方形操场，长40米，宽30米．校园扩建时，长增加到50米，宽增加了8米．扩建后操场的面积是多少公顷？
<gadget id="calculator">30 + 8</gadget>
<output>38</output>

<gadget id="calculator">38 / 10_000</gadget>
<output>19/5_000 = around 0.0038</output>

<gadget id="calculator">50 * (19/5_000)</gadget>
<output>19/100 = around 0.19</output>

<result>19/100 = around 0.19</result>