A right-angled trapezoid, if the lower base is reduced by 3 cm, the trapezoid becomes a square with a side length of 7 cm. What is the area of this trapezoid in cm**2.
一个直角梯形，如果把下底减少3cm，这个梯形就变成一个边长7cm的正方形．这个梯形的面积是多少cm**2．
<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">7 + 10</gadget>
<output>17</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">17 * (7/2)</gadget>
<output>119/2 = around 59.5</output>

<result>119/2 = around 59.5</result>