A right-angled trapezoidal land has an upper base of 50 meters. If the lower base is reduced by 10 meters, the land becomes a square. What is the area of the trapezoid in square meters?
一个直角梯形的土地，上底50米，如果下底减少10米，这块地就成了正方形，这块梯形的面积是多少平方米．
<gadget id="calculator">50 + 50 + 10</gadget>
<output>110</output>

<gadget id="calculator">50 / 2</gadget>
<output>25</output>

<gadget id="calculator">110 * 25</gadget>
<output>2_750</output>

<result>2_750</result>