One base of a right-angled trapezoid is 5 cm. If the other base is reduced by 2 cm, the trapezoid becomes a square. What is the area of this trapezoid in square centimetres.
一个直角梯形的一个底是5厘米，如果把另一个底减少2厘米，这个梯形就变成了一个正方形．这个梯形的面积是多少平方厘米．
<gadget id="calculator">5 + 2 + 5</gadget>
<output>12</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">12 * (5/2)</gadget>
<output>30</output>

<result>30</result>