The shape of a flowerbed is a right-angled trapezoid, with an upper base of 30 meters. If the upper base is increased by 10 meters, it becomes a square flowerbed. How many square meters does this trapezoidal flowerbed occupy?
一个花圃的形状是直角梯形，上底30米，如果把上底增加10米，就成了一个正方形花圃，这个梯形花圃占地多少平方米？
<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">30 + 40</gadget>
<output>70</output>

<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">70 * 20</gadget>
<output>1_400</output>

<result>1_400</result>